Step-by-step Maths Level 4: The 9 pattern and multiplying by 9

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   3 - 1 = 2
2. Find the ones digit. The two digits must add to 9.
   9 - 2 = 7
3. Write the answer. Put the tens digit and the ones digit together.
   27

Check. Check: 2 + 7 = 9, and 27 is 9 × 3.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 11. Multiplying by 10 adds a zero to the end.
   10 × 11 = 110
2. Take away one 11. There is one group of 9 less than ten groups.
   110 - 11 = 99
3. Write the answer. This is 9 groups of the number.
   99

Check. Check: 9 × 11 = 99, so 99 + 11 = 110.

Watch out. This method works for any number, not only the 9 facts.

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   4 - 1 = 3
2. Find the ones digit. The two digits must add to 9.
   9 - 3 = 6
3. Write the answer. Put the tens digit and the ones digit together.
   36

Check. Check: 3 + 6 = 9, and 36 is 9 × 4.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 10. Multiplying by 10 adds a zero to the end.
   10 × 10 = 100
2. Take away one 10. There is one group of 9 less than ten groups.
   100 - 10 = 90
3. Write the answer. This is 9 groups of the number.
   90

Check. Check: 9 × 10 = 90, so 90 + 10 = 100.

Watch out. This method works for any number, not only the 9 facts.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 12. Multiplying by 10 adds a zero to the end.
   10 × 12 = 120
2. Take away one 12. There is one group of 9 less than ten groups.
   120 - 12 = 108
3. Write the answer. This is 9 groups of the number.
   108

Check. Check: 9 × 12 = 108, so 108 + 12 = 120.

Watch out. This method works for any number, not only the 9 facts.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 7. Multiplying by 10 adds a zero to the end.
   10 × 7 = 70
2. Take away one 7. There is one group of 9 less than ten groups.
   70 - 7 = 63
3. Write the answer. This is 9 groups of the number.
   63

Check. Check: 9 × 7 = 63, so 63 + 7 = 70.

Watch out. This method works for any number, not only the 9 facts.

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   12 - 1 = 11
2. Find the ones digit. The two digits must add to 9.
   9 - 11 = -2
3. Write the answer. Put the tens digit and the ones digit together.
   108

Check. Check: 11 + -2 = 9, and 108 is 9 × 12.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 3. Multiplying by 10 adds a zero to the end.
   10 × 3 = 30
2. Take away one 3. There is one group of 9 less than ten groups.
   30 - 3 = 27
3. Write the answer. This is 9 groups of the number.
   27

Check. Check: 9 × 3 = 27, so 27 + 3 = 30.

Watch out. This method works for any number, not only the 9 facts.

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   8 - 1 = 7
2. Find the ones digit. The two digits must add to 9.
   9 - 7 = 2
3. Write the answer. Put the tens digit and the ones digit together.
   72

Check. Check: 7 + 2 = 9, and 72 is 9 × 8.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 4. Multiplying by 10 adds a zero to the end.
   10 × 4 = 40
2. Take away one 4. There is one group of 9 less than ten groups.
   40 - 4 = 36
3. Write the answer. This is 9 groups of the number.
   36

Check. Check: 9 × 4 = 36, so 36 + 4 = 40.

Watch out. This method works for any number, not only the 9 facts.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 5. Multiplying by 10 adds a zero to the end.
   10 × 5 = 50
2. Take away one 5. There is one group of 9 less than ten groups.
   50 - 5 = 45
3. Write the answer. This is 9 groups of the number.
   45

Check. Check: 9 × 5 = 45, so 45 + 5 = 50.

Watch out. This method works for any number, not only the 9 facts.

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   2 - 1 = 1
2. Find the ones digit. The two digits must add to 9.
   9 - 1 = 8
3. Write the answer. Put the tens digit and the ones digit together.
   18

Check. Check: 1 + 8 = 9, and 18 is 9 × 2.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   6 - 1 = 5
2. Find the ones digit. The two digits must add to 9.
   9 - 5 = 4
3. Write the answer. Put the tens digit and the ones digit together.
   54

Check. Check: 5 + 4 = 9, and 54 is 9 × 6.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use the 9 pattern. The digits of each answer add to 9.

1. Find the tens digit. Take 1 from the number you multiply by 9.
   9 - 1 = 8
2. Find the ones digit. The two digits must add to 9.
   9 - 8 = 1
3. Write the answer. Put the tens digit and the ones digit together.
   81

Check. Check: 8 + 1 = 9, and 81 is 9 × 9.

Watch out. The digits always add to 9 in the 9 times table, up to 9 × 10.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 2. Multiplying by 10 adds a zero to the end.
   10 × 2 = 20
2. Take away one 2. There is one group of 9 less than ten groups.
   20 - 2 = 18
3. Write the answer. This is 9 groups of the number.
   18

Check. Check: 9 × 2 = 18, so 18 + 2 = 20.

Watch out. This method works for any number, not only the 9 facts.

Method. Use place value: 9 is 10 take away 1, so 9 times a number is 10 times it take away the number.

1. Work out 10 × 6. Multiplying by 10 adds a zero to the end.
   10 × 6 = 60
2. Take away one 6. There is one group of 9 less than ten groups.
   60 - 6 = 54
3. Write the answer. This is 9 groups of the number.
   54

Check. Check: 9 × 6 = 54, so 54 + 6 = 60.

Watch out. This method works for any number, not only the 9 facts.