Year 1: Doubles and near doubles
Part of the Year 1 adding and subtracting within 20 chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)
Doubles and near doubles
A double is a number added to itself. Double 4 is 4 + 4. The picture has two rows that are the same.
A near double is one more or one less than a double. The picture below has rows of 4 and 5. The 4 + 4 double is 8, and one more makes 4 + 5 = 9.
Key ideas
- A double has two equal rows: 4 + 4 = 8.
- Use a double you know to find a near double.
- Near double: double the smaller number, then add one more.
- Learn the doubles up to 10 + 10 to help with other sums.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 4 is 4 + 4.
- Make two rows of 4. Both rows are the same, so the two numbers are equal.4 and 4
- Count all the things. Count one row, then count the other row.4 + 4 = 8
- Write the answer. 8
Check. Take one row away: 8 − 4 = 4. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 6 first, then add one more.
- Find the double of 6. Double 6 is 6 + 6, two equal groups.6 + 6 = 12
- Add the extra one to 12. 7 is one more than 6, so we add one more.12 + 1 = 13
- Write the answer. 13
Check. Check: start at 7 and count on 6. You also reach 13. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 8 first, then add one more.
- Find the double of 8. Double 8 is 8 + 8, two equal groups.8 + 8 = 16
- Add the extra one to 16. 9 is one more than 8, so we add one more.16 + 1 = 17
- Write the answer. 17
Check. Check: start at 9 and count on 8. You also reach 17. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Watch out
Watch out: a near double is not the double itself. 8 + 9 is one more than 8 + 8. Do not write 16 for 8 + 9. The answer is 17.
Exam tip
Grown-up tip. Put two equal piles of coins or buttons side by side. Ask your child to make a pile one bigger. Then ask: “What is the double? What is one more?”
Exercise 5C Doubles and near doubles
Non-calculatorKey words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 3 is 3 + 3.
- Make two rows of 3. Both rows are the same, so the two numbers are equal.3 and 3
- Count all the things. Count one row, then count the other row.3 + 3 = 6
- Write the answer. 6
Check. Take one row away: 6 − 3 = 3. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 5 is 5 + 5.
- Make two rows of 5. Both rows are the same, so the two numbers are equal.5 and 5
- Count all the things. Count one row, then count the other row.5 + 5 = 10
- Write the answer. 10
Check. Take one row away: 10 − 5 = 5. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 6 is 6 + 6.
- Make two rows of 6. Both rows are the same, so the two numbers are equal.6 and 6
- Count all the things. Count one row, then count the other row.6 + 6 = 12
- Write the answer. 12
Check. Take one row away: 12 − 6 = 6. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 2 is 2 + 2.
- Make two rows of 2. Both rows are the same, so the two numbers are equal.2 and 2
- Count all the things. Count one row, then count the other row.2 + 2 = 4
- Write the answer. 4
Check. Take one row away: 4 − 2 = 2. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 7 is 7 + 7.
- Make two rows of 7. Both rows are the same, so the two numbers are equal.7 and 7
- Count all the things. Count one row, then count the other row.7 + 7 = 14
- Write the answer. 14
Check. Take one row away: 14 − 7 = 7. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 9 is 9 + 9.
- Make two rows of 9. Both rows are the same, so the two numbers are equal.9 and 9
- Count all the things. Count one row, then count the other row.9 + 9 = 18
- Write the answer. 18
Check. Take one row away: 18 − 9 = 9. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 10 is 10 + 10.
- Make two rows of 10. Both rows are the same, so the two numbers are equal.10 and 10
- Count all the things. Count one row, then count the other row.10 + 10 = 20
- Write the answer. 20
Check. Take one row away: 20 − 10 = 10. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 4 first, then add one more.
- Find the double of 4. Double 4 is 4 + 4, two equal groups.4 + 4 = 8
- Add the extra one to 8. 5 is one more than 4, so we add one more.8 + 1 = 9
- Write the answer. 9
Check. Check: start at 5 and count on 4. You also reach 9. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 5 first, then add one more.
- Find the double of 5. Double 5 is 5 + 5, two equal groups.5 + 5 = 10
- Add the extra one to 10. 6 is one more than 5, so we add one more.10 + 1 = 11
- Write the answer. 11
Check. Check: start at 6 and count on 5. You also reach 11. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 6 first, then add one more.
- Find the double of 6. Double 6 is 6 + 6, two equal groups.6 + 6 = 12
- Add the extra one to 12. 7 is one more than 6, so we add one more.12 + 1 = 13
- Write the answer. 13
Check. Check: start at 7 and count on 6. You also reach 13. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 7 first, then add one more.
- Find the double of 7. Double 7 is 7 + 7, two equal groups.7 + 7 = 14
- Add the extra one to 14. 8 is one more than 7, so we add one more.14 + 1 = 15
- Write the answer. 15
Check. Check: start at 8 and count on 7. You also reach 15. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 8 first, then add one more.
- Find the double of 8. Double 8 is 8 + 8, two equal groups.8 + 8 = 16
- Add the extra one to 16. 9 is one more than 8, so we add one more.16 + 1 = 17
- Write the answer. 17
Check. Check: start at 9 and count on 8. You also reach 17. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 9 first, then add one more.
- Find the double of 9. Double 9 is 9 + 9, two equal groups.9 + 9 = 18
- Add the extra one to 18. 10 is one more than 9, so we add one more.18 + 1 = 19
- Write the answer. 19
Check. Check: start at 10 and count on 9. You also reach 19. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A near double is one more or one less than a double.
Method. A near double is one more or one less than a double. Double 7 first, then add one more.
- Find the double of 7. Double 7 is 7 + 7, two equal groups.7 + 7 = 14
- Add the extra one to 14. 8 is one more than 7, so we add one more.14 + 1 = 15
- Write the answer. 15
Check. Check: start at 8 and count on 7. You also reach 15. ✓
Watch out. Do not forget the extra one. The answer is one more than the double.
Key words. A double is two equal amounts, or a number added to itself.
Method. A double is a number added to itself. Double 9 is 9 + 9.
- Make two rows of 9. Both rows are the same, so the two numbers are equal.9 and 9
- Count all the things. Count one row, then count the other row.9 + 9 = 18
- Write the answer. 18
Check. Take one row away: 18 − 9 = 9. One row is left. ✓
Watch out. A double has two equal rows. Do not forget to count the second row.
Method. Find the double first. Then check the extra one.
- Work out 8 + 8. This is the double, and it is correct for the double.8 + 8 = 16
- Work out 8 + 9. 9 is one more than 8, so the total is one more.8 + 9 = 17
- Compare the answers. The answer with the extra one is bigger.16 < 17
- Write the answer. No. 8 + 9 = 17, not 16.
Check. Count on from 16 by one more to reach 17. ✓
Watch out. In a near double, look for the extra one. Do not stop at the double.