Math Problem-Solving Strategies for Various Mathematical Concepts

Explore a variety of math problem-solving scenarios involving multiplication, algebra, geometry, prime numbers, cubes, linear equations, factors, simultaneous equations, and more. Engage in challenges like completing cross-number puzzles, finding the difference between prime numbers, and creatively using digits to solve multiplication sums. Enhance your mathematical skills and logical thinking with these engaging problems.

• Math
• Problem solving
• Multiplication
• Algebra
• Geometry

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1. Problem solving Multiplication Algebra pyramid Perimeter 1 Angles in triangles 1 Multiplication Algebra pyramid Perimeter 1 Angles in triangles 1 Cube numbers Linear equation 1 Perimeter 2 Angles in triangles 2 Cube numbers Linear equation 1 Perimeter 2 Angles in triangles 2 Prime numbers Linear equation 2 Perimeter 3 Angles in triangles 3 Prime numbers Linear equation 2 Perimeter 3 Angles in triangles 3 Prime numbers 2 Linear equation 3 Perimeter 4 Angles in triangles 4 Prime numbers 2 Linear equation 3 Perimeter 4 Angles in triangles 4 Factors Simultaneous equations 1 Area rules 1 Angles in polygons 1 Factors Area rules 1 Simultaneous equations 1 Angles in polygons 1 Multiples 1 Simultaneous equations 2 Area rules 2 Angles in polygons 2 Multiples 1 Area rules 2 Simultaneous equations 2 Angles in polygons 2 Multiples 2 Simultaneous equations 3 Overlapping squares Index laws Multiples 2 Simultaneous equations 3 Overlapping squares Index laws Equivalent ratios Gradient Overlapping circles Fractions 3 Equivalent ratios Gradient Overlapping circles Fractions 3 Percentage of amount Being systematic Visualisation 1 Fractions 4 Being systematic Visualisation 1 Fractions 4 Percentage of amount Fractions 1 Linear equation 4 Visualisation 2 Percentage change Fractions 1 Linear equation 4 Visualisation 2 Percentage change Logic Fractions 2 Constructions Pie charts Logic Fractions 2 Constructions Pie charts

2. Use the digits 1 to 6, once only, in the six boxes to make the multiplication sum correct 4 5 3 1 6 2 How many ways can this be done? Can you be sure? C:\Users\Dan\Downloads\help_256.png

3. Can you complete this cross-number? 2 1 Across Down 1. A cube 3. A cube 1. One less than a cube 3 x The only two-digit cubes are 33 = 27 and 43 = 64 2 1 2 1 Or So either 7 6 2 4 3 3 7 2 6 4 1 Down is one less than a cube so must be 26 C:\Users\Dan\Downloads\help_256.png Hence 3 Across must be 64

4. The sum of three different prime numbers is 40. What is the difference between the two larger primes? 2 must be one of the numbers, as all other primes are odd and there must be exactly two odd numbers to give an even total. So the other two primes add up to 38 The only pair that fits is 7 and 31 Their difference is 24 C:\Users\Dan\Downloads\help_256.png

5. Only one choice of the digit d gives prime numbers when you read across and down in the diagram below. Which digit is d? 5 d 7 1 3 A 5 B 6 C 7 Hint: consider the test for divisibility by 3 Vertically, 5 + 7 = 12 so d cannot be 6 Horizontally, 1 + 3 = 4 so d cannot be 5 Which leaves d = 7 C:\Users\Dan\Downloads\help_256.png

6. A census taker approaches a house and asks the woman who answers the door "How many children do you have, and what are their ages?" Woman: "I have three children, the product of their ages are 36, the sum of their ages are equal to the address of the house next door." The census taker walks next door, comes back and says "I need more information." The woman replies "I have to go, my oldest child is sleeping upstairs." Census taker: "Thank you, I now have everything I need." What are the ages of each of the three children? The possible ages, based on their product being 36: Product Sum 1 1 1 1 1 2 2 3 36 18 12 4 6 2 3 3 1 2 3 38 21 16 14 13 13 11 10 Looking at the house number next door is only inconclusive if the number is 13, as there are two combinations with this sum 9 6 9 6 4 As the woman has an oldest child, they must be the 2, 2 and 9 combination! C:\Users\Dan\Downloads\help_256.png

7. What is the largest multiple you can make using the digits below? You don t have to use each digit and can use each one at most once 2 3 4 5 Multiple of 2 Multiple of 3 Multiple of 6 Digits must sum to a multiple of 3 Number must be even Must be a multiple of 2 and 3 5432 Don t use the 2 as this is the smallest value you can remove to obtain a multiple of 3 534 543 What are the smallest and largest multiples of 4 you can make using all the digits below? Last 2 digits must be divisible by 4 4 5 6 7 8 C:\Users\Dan\Downloads\help_256.png Smallest 45768 Largest 87564

8. Beth, Carol and George love reading their favourite bedtime story together. They take it in turns to read a page, always in the order Beth, then Carol, then George. All twenty pages of the story are read on each occasion. One evening, Beth is staying at Grandma s house but Carol and George still read the same story and take it in turns to read a page with Carol reading the first page. In total, how many pages are read by the person who usually reads that page? Carol normally reads the 2nd, 5th, 8th, pages but on this occasion reads every odd page. These coincide on the 5th, 11th, 17th pages. George normally reads the 3rd, 6th, 9th, pages but on this occasion reads every even page. These coincide on the 6th, 12th, 18th pages. This gives a total of 6 pages read by the usual person C:\Users\Dan\Downloads\help_256.png

9. In a sale, an item is reduced by 20% and as a result makes only a 4% profit on the cost to the shop-keeper. What percentage profit would the shop-keeper have made if the item had sold at full price? c = cost price s = selling price . 1 = 8 . 0 = 04 = s c You know that 3 . 1 = c 10 4 . s c c . 1 04 i.e. 30% profit 8 8 . 0 C:\Users\Dan\Downloads\help_256.png

10. A swimming club has junior, senior and veteran members. The ratio of juniors to seniors is 3:2 The ratio of seniors to veterans is 5:2 Which of the following could be the total number of members in the club? A 30 B 35 C 48 D 58 E 60 J : S : V 3 : 2 x 5 15 : 10 : 4 x 2 5 : 2 Which total could be shared in the ratio 15 : 10 : 4? Only 58 C:\Users\Dan\Downloads\help_256.png

11. After playing 500 games, my success rate at Angry Birds is 49%. Assuming I win every game from now on, how many extra games do I need to play in order that my success rate increases to 50%? (a) 1 (b) 2 (c) 5 (d) 10 (e) 50 1% of 500 is 5, so 49% is 245 games won so far 246 50 If I win 1 more, this gives % 501 247 50 If I win 2 more, this gives 502 % 250 50 If I win 5 more, this gives 505 % 255 = 50 If I win 10 more, this gives 510 % I must play 10 more times C:\Users\Dan\Downloads\help_256.png

12. A cube with 3cm sides is painted red on the outside. The cube is then split into cubes with 1cm sides. What fraction of the total surface area of the new cubes is red? 3 sides painted = 8 2 sides painted = 1 x 12 = 12 1 side painted = 1 x 6 = 6 No sides painted = 1 Total = 27 + + = + + = = 8 6 9 1 12 1 1 4 4 1 1 27 2 27 3 27 6 27 27 27 27 3 C:\Users\Dan\Downloads\help_256.png

13. The numbers 2, 3, 4, 5, 6, 7, 8 are to be placed, one per square, in the diagram shown such that the four numbers in the horizontal row and the four numbers in the vertical column add up to 21. Which number should replace x? Total in all squares = 2+3+4+5+6+7+8 = 35 Total of row + column = 42 But this is the total on all squares + x x So x = 7 C:\Users\Dan\Downloads\help_256.png

14. 1+ 1 What is the value of 6 2 2 6 1+ = + = + = + 2 4 1 1 1 1 1 3 2 ( )2 6 2 6 6 2 2 6 2 6 2 2 6 2 2 2 3 2 3 2 3 2 3 = 25 63 2 2 = 2 5 ( ) 2 3 2 3 ( ) 24 2 = 5 + = 5 1 1 24 6 2 2 6 C:\Users\Dan\Downloads\help_256.png

15. In this number pyramid, the two numbers below are a block are added to give its value. Find the value of x + + = 360 270 a b x x x = + + 102 a 168 b +b = 90 a + + 78 12 b a 90 a 78 b 12 C:\Users\Dan\Downloads\help_256.png

16. John, Paul, George and Ringo have their 12th, 14th, 15th and 15th birthdays today. How many years will it be till their combined age reaches 100? If n years pass, their ages will be: + 12 n John: + 14 n Paul: + 15 n George: + 15 n Ringo: 56+ 4 n Total: + n = 56 ) ) 4 100 Now solve the equation ( 4 = n ( 44 56 = 11 4 n In 11 years time C:\Users\Dan\Downloads\help_256.png

17. Three-quarters of the area of the rectangle has been shaded. What is the value of x? ( ) x = = = + + 24 6 8 x 2 x Unshaded areas 2 2 ( ) x 4 6 x 2 3 x ( ) x 3 = 4 24 So rectangle area 6 But rectangle area = 6 x 8 = 48 x = 24 3 12 x = 4 6 C:\Users\Dan\Downloads\help_256.png

18. Q is an enlargement of P, scale factor 3, from centre O. Find the value of x + 3 x 2 x O P Q ( 3 ) ( = 6 = ) ( + 1 ) 3 + + 3 2 2 x x x 2 x x x = 7 C:\Users\Dan\Downloads\help_256.png

19. Peter has three times as many sisters as brothers. His sister Louise has twice as many sisters as brothers. How many children are there in the family? Let b = number of boys and g = number of girls ( ) = 3 1 (1 b g ) Peter has three times as many sisters as brothers = 2 1 (2 b g ) Louise has twice as many sisters as brothers (1 = ) 3 3 = b g 3 3 b g + 2 = b 1 (2 g ) = = 4 9 b g Sub in (2) There are 4 + 9 = 13 children C:\Users\Dan\Downloads\help_256.png

20. C:\Users\Dan\Downloads\help_256.png Wobbly weights Weighing the baby at the clinic was a problem The baby would not keep still and caused the scales to wobble So I held the baby and stood on the scales while the nurse read off 78 kg Then the nurse held the baby while I read off 69 kg +b +b +n = = = 78 69 137 p n p + Finally I held the nurse while the baby read off 137 kg What is the combined weight of all three? + + n = = 2 2 2 + 284 142 p n + b b Weight of parent = p p Weight of nurse = n Weight of baby = b A 142 kg B 147 kg C 206 kg D 215 kg E 284 kg

21. I write down three positive numbers a, b and c The product of a and b is 2. The product of b and c is 24. The product of c and a is 3. What is the sum of all three numbers? = ab 24 = bc 3 = ac ( ) 3 ( ) ( ) ( ) 3 2 1 ( ) 1 ( ) 2 2 ( ) = 2 2 2 2 24 3 2= a b c abc = abc 12 144 c a b = = = 6 1 Comparing with equation (1) Comparing with equation (2) Comparing with equation (3) 2 4 So sum is 10 C:\Users\Dan\Downloads\help_256.png

22. The two shapes are made up of the same pieces. Where did the hole come from? Gradient = 5 2 Gradient = 7 3 Hence the shapes are different (and neither is a triangle!) C:\Users\Dan\Downloads\help_256.png

23. The interior angles of a triangle are (5x+3y)o, (3x+20)o and (10y+30)o where x and y are whole numbers. What is the value of x+y? (a) 15 (b) 14 (c) 13 (d) 12 (e) 11 + + 8 13 50 x y Summing angles gives ( ) + y x 3 5 But the angles in a triangle sum to 180o 13 8 + x Hence = 130 y To understand the effect of the different values offered for x+y, factorise to obtain ( ) ( ) ( ) +20 +30 3x + + = 10y 8 5 130 x y y Trying the different options: y y y y y = = = = = y y y y y 5 = 5 = 5 = 5 = 5 = + y + y + y + y + y = = = = = 2 3. 5. 6. 8. 10 18 26 34 42 15 14 13 12 11 x x x x x which is possible 6 2 8 4 which is not a whole number which is not a whole number which is not a whole number which is not a whole number C:\Users\Dan\Downloads\help_256.png The only answer giving whole numbers is (a) 15

24. There are six more girls than boys in Miss Spellings class of 24 pupils. What is the ratio of girls to boys in this class? (a) 5:3 (b) 4:1 (c) 3:1 (d) 1:4 (e) 3:5 Number of boys = x Number of girls = x + 6 Total pupils = 2x + 6 But total = 24 x + 2 = = 2 x x 6 24 18 9 = 9 boys 15 girls Ratio girls to boys = 15:9 = 5:3 C:\Users\Dan\Downloads\help_256.png

25. What is the value of the expression ) ( ) ( ( ) ( ) ( ) + + + + + 1 1 1 ... 1 1 1 1 1 1 1 2 3 4 998 999 3 4 5 999 1000 = ... 500 2 3 4 998 999 C:\Users\Dan\Downloads\help_256.png

26. The shape shown is made up of three rectangles, each measuring 3cm by 1cm. What is the perimeter of the shape? Perimeter of rectangles = 3 x 8 = 24 Meeting edges = 2 x (3 + 1) = 8 16cm C:\Users\Dan\Downloads\help_256.png

27. Each side of an isosceles triangle is a whole number of cm. Its perimeter is 20cm. How many possibilities are there for the length of its sides? 1, 1, 18 2, 2, 16 3, 3, 14 Not possible 4, 4, 12 5, 5, 10 The equal sides must have a total length which is greater than the length of the third side 6, 6, 8 7, 7, 6 8, 8, 4 9, 9, 2 There are 4 possibilities C:\Users\Dan\Downloads\help_256.png

28. The parallelogram shown in the diagram has been divided into nine smaller parallelograms. The perimeters, in cm, of four of the smaller parallelograms are shown. The perimeter of WXYZ is 21cm. What is the perimeter of the shaded parallelogram? f C:\Users\Dan\Downloads\help_256.png d e W c X 4 b 11 5 a 8 Z Y ( c ( ) ) ( ) ( ) f = + + + + + + + 2 2 2 2 a e e b d b Total perimeter for given shapes ( ) ( ) e = + Perimeter of WXYZ + + + + + + 2 2 Perimeter of shaded shape a b c d e f b ( ) 21 = = + + + 7 8 4 11 5 So perimeter of shaded shape

29. A 3 x 8 rectangle is cut into two pieces along the dotted line shown. The two pieces are then rearranged to form a right-angled triangle. What is the perimeter of the triangle formed? Perimeter = 24cm 10cm 6cm 3cm 8cm C:\Users\Dan\Downloads\help_256.png

30. Which shapes area is different to the others? A B C = 3 2 3 = 1 3 3 2 = 3 3 2 2 D E = 1 3 3 Hard to tell come back to it! As the others are all definitely 3, this must be the odd one out! Can you work out D s area? ( ) 2 2 9 C:\Users\Dan\Downloads\help_256.png = 2 2 3 1 1 2 2

31. The area of JGK is 20cm2 Can you find the areas of every other shape? 4 4 4 A B C D = 8 4 4 2 4 ( ) = 4 4 16 4 = 4 24 + 4 8 2 ADHK is a square, length 12 cm F G E AB = BC = CD = AE 4 8 BE is parallel to CF = 32 8 8 EI is parallel to FJ 2 GE is parallel to AD 8 = 4 8 32 8 8= 20 ? 2 = 12 3 8 2 3 4 5 H I J K C:\Users\Dan\Downloads\help_256.png

32. Three identical squares overlap as shown. The areas of the overlapping sections are 2cm2, 5cm2 and 8cm2. The areas of the non-overlapping parts of the squares are 117cm2. What are the lengths of the sides of the squares? Total area = non-overlapping + 2 x overlapping = 117 + 2 x (2 + 5 + 8) = 147cm2 Each square = 49cm2 Side of each square = 7cm C:\Users\Dan\Downloads\help_256.png

33. Prove that the red areas and the pink areas are the same If radius of small circles = r ( )2 2r = = 4 r 2 large circle = small circles So overlap = remainder ie red = pink C:\Users\Dan\Downloads\help_256.png

34. Imagine two identical isosceles triangles. Put sides of equal length together. Describe the resulting shape. Is it the only possibility? Rhombus Kite Parallelogram If the isosceles triangles were right-angled Isosceles triangle Square C:\Users\Dan\Downloads\help_256.png

35. A solid square-based pyramid has all of its corners cut off, as shown. How many edges does the resulting shape have? 8 + 4 + 4 x 3 = 24 C:\Users\Dan\Downloads\help_256.png

36. The diagram shows two equilateral triangles. Find the size of angle x x 80o60o 80o x = 40o 60o 60o 75o 65o 55o 45o C:\Users\Dan\Downloads\help_256.png

37. In this triangle, the internal bisectors of the angles at Q and R meet at S. What is the size of angle QSR? P PQR + PRQ = 140o 40o so SQR + SRQ = 70o S then QSR = 110o Q R C:\Users\Dan\Downloads\help_256.png

38. What is the sum of the six marked angles? Five points make 5 x 360 = 1800o Two triangles make 2 x 180 = 360o 1440o C:\Users\Dan\Downloads\help_256.png

39. What is the sum of the marked angles now?! Four triangles make 720o Quadrilateral makes 360o 360o C:\Users\Dan\Downloads\help_256.png

40. The diagram a regular pentagon and a regular hexagon which overlap. Find the size of angle x 36o 60o x x = 84o C:\Users\Dan\Downloads\help_256.png

41. A pupil has three tiles. One is a regular octagon, one is a regular hexagon, and one is a square. The side length of each tile is the same. The pupil says the hexagon will fit exactly like this. Why is the pupil wrong? Interior angle of square = 90o Interior angle of hexagon = 120o 90 135 Interior angle of octagon = 135o 90 + 120 + 135 = 345o 120 As the total angle is less than 360o, the shapes will not meet exactly at a point Diagram not drawn accurately C:\Users\Dan\Downloads\help_256.png

42. = + + + Solve x 2 2 2 2 2 = x 2 4 2 1 = 2 x 2 2 2 2 1 2 2 = x 2 2 x = 2 1 2 C:\Users\Dan\Downloads\help_256.png

43. The diagram shows a square with side length 1, divided into four rectangles whose areas are equal. What is the length labelled x? x 3 1 = 1 x 3 4 8 4 8 3 1 = 1 8 4 4 4 3 = 1 8 4 12 = 2 3 1 1 4 4 C:\Users\Dan\Downloads\help_256.png 1

44. Only one of these triangles can actually be made. Which is it? Not possible triangle can t be isosceles with these angles Not possible must be that the longer the side, the bigger the angle opposite 25o 20o 3cm B A 4cm 4cm 130o 30o 25o 110o 5cm C 3cm 7cm 8cm Not possible Pythagoras theorem doesn t hold 2 7 4 + 30o 2cm D 6cm 2 2 8 6cm E 3cm 60o 3cm Hard to tell come back to it! As the others are all impossible, so this one must be (in fact it is half an equilateral triangle with 6cm sides!) Not possible the longest side must be less than the sum of the other two C:\Users\Dan\Downloads\help_256.png

45. What frequencies for green, red, blue and yellow could create these pie charts? a b c = = green= = blue 2 6 red yellow yellow red 3 yellow If frequency of green = n green red blue yellow n 6 3 n n n frequencies? C:\Users\Dan\Downloads\help_256.png