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Math · Multiplication & Mathematical Reasoning
Multiplication and Division Facts: Arrays, Fact Families, Break Apart
Use arrays and fact families to link multiplication and division, and break hard facts like 7 × 8 into easier ones you already know.
The idea
In the last few lessons you added, subtracted and estimated with bigger numbers. Today you go back to the facts that make all of that faster: multiplication and division facts. Knowing them well saves time, and knowing how to rebuild a fact you forget saves more.
An array is objects in equal rows and equal columns. If there are 6 rows with 4 counters in each row, there are 6 × 4 = 24 counters. Turn the array a quarter turn and it becomes 4 rows of 6, so 4 × 6 = 24 too. Multiplication can be done in either order.
Multiplication and division undo each other. Three numbers that belong together make a fact family. For 6, 7 and 42 the family is 6 × 7 = 42, 7 × 6 = 42, 42 ÷ 6 = 7 and 42 ÷ 7 = 6. The product is always the biggest number, and it is the number you divide. This is why a division fact is a missing-factor question: 56 ÷ 8 asks “8 times what is 56?”
When you do not remember a fact, break one factor apart into two easy facts and add. For 7 × 8, split the 8 into 5 + 3. Then 7 × 5 = 35 and 7 × 3 = 21, and 35 + 21 = 56. In the array, you cut 8 columns into a group of 5 columns and a group of 3 columns.
Other helpers work the same way. Doubles: 6 × 8 is double 3 × 8, so 24 + 24 = 48. Neighbour facts: 7 × 8 is one group of 8 less than 8 × 8, so 64 − 8 = 56. Nines: 9 × 7 is 10 × 7 take away one group of 7, so 70 − 7 = 63. Notice that you always add or take away whole groups, never just 1.
Be careful with order. Turn-around works for multiplication (6 × 8 = 8 × 6) but not for division (48 ÷ 6 = 8, but 6 ÷ 48 is less than 1). Always check a division answer by multiplying back: if 8 × 6 = 48, then 48 ÷ 6 = 8 and 48 ÷ 8 = 6.
Worked examples
Example 1 · Read an array
An array has 6 rows with 4 counters in each row. How many counters is that?
- Rows are equal groups, and each row holds 4.
- 6 rows of 4 is 6 × 4.
- Count by 4s six times: 4, 8, 12, 16, 20, 24.
- Turn the array: 4 rows of 6 is 4 × 6 = 24 as well.
24
Example 2 · Break apart a fact
Find 7 × 8 using facts you know.
- Split 8 columns into 5 columns and 3 columns.
- 7 × 5 = 35 and 7 × 3 = 21.
- Add the two parts: 35 + 21 = 56.
- Check with the neighbour fact: 8 × 8 = 64, and 64 − 8 = 56.
56
Example 3 · Fact family
Write the fact family for 6, 7 and 42.
- The product is the biggest number: 42.
- Two multiplication facts: 6 × 7 = 42 and 7 × 6 = 42.
- Two division facts divide 42 by each factor: 42 ÷ 6 = 7 and 42 ÷ 7 = 6.
- Every fact uses only 6, 7 and 42.
6 × 7 = 42, 7 × 6 = 42, 42 ÷ 6 = 7, 42 ÷ 7 = 6
Example 4 · Division as a missing factor
Find 56 ÷ 8.
- Ask: 8 times what number is 56?
- Skip count by 8s: 8, 16, 24, 32, 40, 48, 56. That is 7 jumps.
- So 8 × 7 = 56 and 56 ÷ 8 = 7.
- Multiply back to check: 7 × 8 = 56.
7
Example 5 · Catch the mistake
Mia says 7 × 6 = 48 because 7 × 7 = 49 and 49 − 1 = 48. Is she right?
- 6 groups of 7 is one whole group of 7 fewer than 7 groups of 7.
- She took away 1, not 7.
- 49 − 7 = 42.
- Check: 6 × 7 = 42 and 42 ÷ 7 = 6.
No. The answer is 42.
Common mistakes
These are tempting because they use familiar operations. Check what the question is actually measuring.
Why this fails: 6 rows of 4 is 6 × 4 = 24, not 6 + 4 = 10. Multiplication counts equal groups.
Why this fails: 7 × 6 is 7 × 7 − 7 = 42, not 49 − 1 = 48. When you change a factor by 1, the product changes by a whole group.
Why this fails: 48 ÷ 6 = 8, but 6 ÷ 48 is less than 1. The product, or the total, goes first in a division fact.
Why this fails: 8 × 6 = 48 does not tell you 56 ÷ 8 is 6. Multiply back to check: 8 × 7 = 56, so the answer is 7.
Why this fails: 4 × 9 = 9 × 4, but 12 ÷ 3 is not 3 ÷ 12. Only multiplication can be done in either order.
Why this fails: Multiply back to check a division, and divide to check a multiplication. If 8 × 7 = 56, then 56 ÷ 8 must be 7.
Foundation
Foundation practice
Read arrays, link repeated addition to multiplication, and use fact families for division.
1. An array has 6 rows with 4 counters in each row. How many counters are there in all?
- 10
- 24
- 18
- 28
2. 4 + 4 + 4 + 4 + 4 + 4 + 4 has seven 4s. Which multiplication fact matches it?
- 4 × 4 = 16
- 7 + 4 = 11
- 7 × 7 = 49
- 7 × 4 = 28
3. 3 × 8 = 24. Which division fact belongs to the same fact family?
- 24 ÷ 8 = 3
- 8 ÷ 24 = 3
- 24 − 8 = 16
- 3 ÷ 8 = 24
4. You know that 9 × 6 = 54. What is 6 × 9?
- 45
- 15
- 54
- 63
5. What number makes this true? ___ × 7 = 56
- 7
- 9
- 49
- 8
6. 35 stickers are shared equally among 5 friends. How many stickers does each friend get?
- 30
- 7
- 40
- 175
7. Count by 8s: 8, 16, 24, 32, ___. What comes next?
- 36
- 42
- 40
- 48
8. Which statement is true?
- 9 × 0 = 0
- 9 × 0 = 9
- 9 ÷ 1 = 1
- 0 ÷ 9 = 9
Practice
Practice practice
Break hard facts into easy ones: doubles, neighbour facts, the nines trick and word problems.
9. Which pair of smaller facts can you add to find 7 × 8?
- 7 × 5 + 7 × 4
- 7 × 4 + 3
- 7 × 5 + 7 × 3
- 7 × 5 + 3
10. You know 3 × 8 = 24. Use it to find 6 × 8.
- 48
- 27
- 32
- 24
11. You know 8 × 8 = 64. Use it to find 7 × 8.
- 72
- 63
- 57
- 56
12. Use 10 × 7 = 70 to find 9 × 7.
- 77
- 63
- 70
- 56
13. Chairs are set out in 9 rows of 6 for a school concert (invented example). How many chairs are there?
- 15
- 45
- 54
- 63
14. 48 pencils are packed in boxes of 6 (invented example). How many boxes are filled?
- 42
- 288
- 7
- 8
15. Which number sentence belongs to the fact family for 6, 9 and 54?
- 54 ÷ 6 = 9
- 54 ÷ 9 = 9
- 6 + 9 = 54
- 9 ÷ 54 = 6
16. Which description shows the same number of counters as 4 rows of 6?
- 4 rows of 10
- 6 rows of 4
- 5 rows of 5
- 6 rows of 6
Think
Think practice
Find the error, choose the operation and decide which turn-around ideas really work.
17. Mia wrote 7 × 6 = 48 because “7 × 7 is 49, and 49 − 1 is 48.” What went wrong?
- She should have added 7 to 49.
- 7 × 7 is not 49.
- Nothing; 48 is correct.
- She took away 1 instead of one whole group of 7.
18. Jay wrote 56 ÷ 8 = 6 because “8 × 6 = 48.” Which statement is correct?
- He should have multiplied 56 × 8.
- He used the wrong fact: 8 × 6 is 48, not 56. The answer is 7.
- He should have added 56 + 8.
- Nothing; 6 is correct.
19. Which pair of expressions always has equal values?
- 12 ÷ 3 and 3 ÷ 12
- 20 − 8 and 8 − 20
- 4 × 9 and 9 × 4
- 10 ÷ 5 and 5 ÷ 10
20. Which situation needs 36 ÷ 4?
- 36 cards are dealt equally to 4 players. How many cards does each player get?
- 4 packs each hold 36 cards. How many cards are there in all?
- You have 36 cards and find 4 more. How many cards now?
- You have 36 cards and give away 4. How many are left?
21. Which product is the greatest?
- 6 × 8
- 9 × 5
- 7 × 7
- 4 × 11
22. A rectangle of 45 tiles has 5 rows. How many tiles are in each row?
- 40
- 9
- 50
- 8
23. Which number of counters can NOT be arranged in 3 equal rows with none left over?
- 27
- 24
- 30
- 26
24. Sam counted by 6s: 6, 12, 18, 24, 32, 36. Which number in his count is wrong?
- 32
- 12
- 24
- 36
Challenge
Challenge practice
Use two clues, two steps and your own explanations to show how the facts connect.
25. Two whole numbers have a product of 54 and a sum of 15. What are they?
- 7 and 8
- 6 and 9
- 5 and 10
- 3 and 12
26. Which number between 50 and 60 is in the 8 times table?
- 54
- 58
- 56
- 60
27. 7 rows of 4 desks are set up (invented example). Then 8 desks are removed and the rest are put into groups of 5. How many groups of 5 are there?
- 5
- 20
- 8
- 4
28. A fact family uses 8, 9 and 72. How many different multiplication and division facts can you write with these three numbers?
- 4
- 2
- 3
- 6
29. Which expression does NOT have the same value as 6 × 12?
- 6 × 10 + 6 × 2
- 6 × 10 + 2
- 3 × 12 + 3 × 12
- 6 × 6 + 6 × 6
30. Explain why 7 × 8 = 7 × 5 + 7 × 3. Describe or sketch an array to support your answer.
31. Write all four facts in the fact family for 6, 7 and 42.
32. Maya says: “8 × 6 = 6 × 8, so 48 ÷ 6 must equal 6 ÷ 48.” Is she right? Explain.
Answer key
- 1. 24
6 rows of 4 is 6 × 4 = 24. 10 comes from adding 6 + 4 instead of making equal groups, 18 is 6 × 3 (one column short), and 28 is 7 × 4 (one row too many). - 2. 7 × 4 = 28
Seven equal groups of 4 is 7 × 4 = 28. 4 × 4 counts only four fours, 7 + 4 adds the group count to the group size instead of multiplying, and 7 × 7 uses the number of groups as the size too. - 3. 24 ÷ 8 = 3
A fact family uses the same three numbers, and the product is the number you divide. 24 ÷ 8 = 3 undoes 3 × 8. 8 ÷ 24 and 3 ÷ 8 divide by or into the wrong numbers (neither equals the stated result), and 24 − 8 is subtraction, not division. - 4. 54
Multiplying in either order gives the same product: 6 rows of 9 is the same array as 9 rows of 6, turned a quarter turn. 45 swaps the digits of 54, 15 adds 9 + 6, and 63 is 7 × 9. - 5. 8
Think 56 ÷ 7 = 8, because 8 × 7 = 56. 7 would give 49, 9 would give 63, and 49 is 56 − 7 (taking away one group’s worth instead of dividing). - 6. 7
Equal sharing is division: 35 ÷ 5 = 7, because 5 × 7 = 35. 30 is 35 − 5 and 40 is 35 + 5, which do not describe equal sharing, and 175 multiplies instead of dividing. - 7. 40
Each count adds 8: 32 + 8 = 40. 36 adds 4 (counting by 4s), 42 adds 10, and 48 skips a number (that is two jumps of 8 from 32). - 8. 9 × 0 = 0
Zero groups, or groups of zero, hold nothing: 9 × 0 = 0. 9 × 0 = 9 mixes up multiplying by zero with adding zero. 9 ÷ 1 = 9 (not 1) because one group holds all 9. 0 ÷ 9 = 0 because sharing nothing gives nothing. - 9. 7 × 5 + 7 × 3
8 columns split as 5 + 3, so 7 × 8 = 7 × 5 + 7 × 3 = 35 + 21 = 56. 7 × 5 + 7 × 4 splits 8 as 5 + 4 and gives 63, and the last two add a plain 3 or use only part of the array instead of 3 whole columns of 7. - 10. 48
6 is double 3, so 6 × 8 is double 3 × 8: 24 + 24 = 48. 24 forgets to double, 27 adds 3 instead of 3 more groups of 8, and 32 is 4 × 8. - 11. 56
7 × 8 is one group of 8 fewer than 8 × 8, so subtract 8: 64 − 8 = 56. 72 adds a group instead, 57 subtracts 7 (one, not eight), and 63 is 7 × 9. - 12. 63
9 × 7 is one group of 7 less than 10 × 7: 70 − 7 = 63. 77 adds a group, 70 is the 10 × 7 fact itself, and 56 is 8 × 7 (two groups too few). - 13. 54
9 rows of 6 is 9 × 6 = 54. 15 adds 9 + 6, 45 is 9 × 5 (a near-miss fact), and 63 is 9 × 7. - 14. 8
Find how many 6s fit in 48: 48 ÷ 6 = 8, because 6 × 8 = 48. 42 subtracts 6, 288 multiplies instead of dividing, and 7 comes from 6 × 7 = 42, a near-miss fact. - 15. 54 ÷ 6 = 9
The product 54 is the number being divided: 54 ÷ 6 = 9. 54 ÷ 9 is 6, not 9, 6 + 9 is only 15, and 9 ÷ 54 divides the small number by the big one. - 16. 6 rows of 4
4 rows of 6 and 6 rows of 4 are both 24 counters. 4 rows of 10 is 40, 5 rows of 5 is 25 (close but not equal), and 6 rows of 6 is 36. - 17. She took away 1 instead of one whole group of 7.
6 groups of 7 is one group of 7 fewer than 7 groups of 7: 49 − 7 = 42. Taking away only 1 leaves 48. Adding 7 would give 56, 7 × 7 really is 49, and 7 × 6 is 42, so 48 is not correct. - 18. He used the wrong fact: 8 × 6 is 48, not 56. The answer is 7.
To check a division answer, multiply back: 8 × 6 = 48, which does not rebuild 56. 8 × 7 = 56, so 56 ÷ 8 = 7. Multiplying or adding would not find an equal-share amount, and 6 fails the multiply-back check. - 19. 4 × 9 and 9 × 4
Multiplication can be done in either order (4 × 9 = 9 × 4 = 36). Division and subtraction cannot: 12 ÷ 3 = 4 but 3 ÷ 12 is only one quarter, 20 − 8 = 12 but 8 − 20 is below zero, and 10 ÷ 5 = 2 but 5 ÷ 10 is one half. - 20. 36 cards are dealt equally to 4 players. How many cards does each player get?
Dealing 36 cards equally among 4 players is division: 36 ÷ 4 = 9. Four packs of 36 is 4 × 36 = 144, finding 4 more is 36 + 4 = 40, and giving away 4 is 36 − 4 = 32. - 21. 7 × 7
7 × 7 = 49, 6 × 8 = 48, 9 × 5 = 45 and 4 × 11 = 44. Having the largest factor (9 or 11) does not make the largest product; calculate each one. - 22. 9
Rows × tiles per row = 45, so 45 ÷ 5 = 9. 40 is 45 − 5, 50 is 45 + 5, and 8 comes from the near-miss fact 5 × 8 = 40. - 23. 26
Equal rows of 3 need a multiple of 3. 27 = 3 × 9, 24 = 3 × 8 and 30 = 3 × 10, but 26 ÷ 3 is 8 with 2 left over. - 24. 32
24 + 6 = 30, so the fifth number should be 30, not 32. The 12, 24 and 36 are all in the 6 times table (2 × 6, 4 × 6 and 6 × 6). - 25. 6 and 9
6 × 9 = 54 and 6 + 9 = 15. 7 and 8 also add to 15 but multiply to 56, 5 and 10 add to 15 but multiply to 50, and 3 and 12 add to 15 but multiply to 36. Both clues must work. - 26. 56
8 × 7 = 56 is the only multiple of 8 from 51 to 59. 54 = 9 × 6 is a different table, 58 is not a multiple of 8 (58 ÷ 8 leaves 2), and 60 is outside the range (and 60 ÷ 8 leaves 4). - 27. 4
7 × 4 = 28 desks, 28 − 8 = 20 desks left, and 20 ÷ 5 = 4 groups. 5 forgets to remove desks (28 ÷ 5 is about 5), 20 stops before grouping, and 8 is the number removed. - 28. 4
The four facts are 8 × 9 = 72, 9 × 8 = 72, 72 ÷ 8 = 9 and 72 ÷ 9 = 8. Two counts only one multiplication and one division, three leaves one out, and six counts facts that are repeats or do not exist. - 29. 6 × 10 + 2
6 × 12 = 72. 6 × 10 + 2 = 62 because the 2 was not multiplied by 6. The others all make 72: 60 + 12, 36 + 36 and 36 + 36. - 30. An array of 7 rows and 8 columns can be cut into 5 columns and 3 columns. The 5-column part has 7 × 5 = 35 counters, the 3-column part has 7 × 3 = 21, and 35 + 21 = 56 = 7 × 8.
Self-review with this: did you split one factor into two smaller parts (8 = 5 + 3), multiply each part by the other factor (7), and add the two products? Splitting works because every counter is in exactly one part. Check: 7 × 8 = 56 and 35 + 21 = 56. - 31. 6 × 7 = 42, 7 × 6 = 42, 42 ÷ 6 = 7, 42 ÷ 7 = 6.
The two multiplication facts use the same factors in either order, and the two division facts divide the product by each factor. Self-review: did every fact use only 6, 7 and 42, with 42 as the product or the number being divided? - 32. No. Multiplication can be done in either order, but division cannot. 48 ÷ 6 = 8, while 6 ÷ 48 is less than 1 (one eighth).
Self-review: did you test both divisions? 48 ÷ 6 = 8 because 6 × 8 = 48. Dividing 6 by 48 asks how many 48s fit in 6, which is less than one whole. Turn-around only works for multiplication.