Year 1: Counting in 2s, 5s and 10s
Part of the Year 1 grouping and sharing chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)
Counting in 2s, 5s and 10s
When we count in 2s, we jump on by 2 each time: 2, 4, 6, 8. When we count in 5s, we jump on by 5: 5, 10, 15, 20. When we count in 10s, we jump on by 10: 10, 20, 30, 40.
Look at the boxes. Each box has 2 biscuits. Counting in 2s is a quick way to count them.
Key ideas
- Counting in 2s means jumping on by 2 each time.
- Counting in 5s means jumping on by 5 each time.
- Counting in 10s means jumping on by 10 each time.
- Every jump is the same size.
Key words. Counting in 2s means jumping on by 2 each time.
Method. Count in 2s. Every jump is the same size: 2.
- Start at 2. Put your finger on the first number.2
- Jump on by 2 each time. Each number is 2 more than the one before.2 + 2 = 4
4 + 2 = 6
6 + 2 = 8
8 + 2 = 10
10 + 2 = 12 - Write the numbers. Say them in order, one jump at a time.2, 4, 6, 8, 10, 12
Check. Count back in 2s from 12 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 2 more than the one before.
Key words. Counting in 2s means jumping on by 2 each time.
Method. Count in 2s. Every jump is the same size: 2.
- Start at 2. Put your finger on the first number.2
- Jump on by 2 each time. Each number is 2 more than the one before.2 + 2 = 4
4 + 2 = 6
6 + 2 = 8 - Write the numbers. Say them in order, one jump at a time.2, 4, 6, 8
Check. Count back in 2s from 8 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 2 more than the one before.
Key words. Counting in 5s means jumping on by 5 each time.
Method. Count in 5s. Every jump is the same size: 5.
- Start at 5. Put your finger on the first number.5
- Jump on by 5 each time. Each number is 5 more than the one before.5 + 5 = 10
10 + 5 = 15
15 + 5 = 20
20 + 5 = 25
25 + 5 = 30 - Write the numbers. Say them in order, one jump at a time.5, 10, 15, 20, 25, 30
Check. Count back in 5s from 30 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 5 more than the one before.
Watch out
Watch out: keep the same jump all the way. 2, 4, 6, 9 is wrong, because the last jump is not 2.
Exam tip
Grown-up tip. Count out loud together. Use pairs of socks for 2s, one hand for 5s and two hands for 10s. Ask: “What is the next number?” before your child says it.
Exercise 9A Counting in 2s, 5s and 10s
Non-calculatorMethod. Count in 2s. Each number is 2 more than the one before it.
- Look at the numbers before and after each gap. The jump is the same every time.2, 4, ?, 8, ?, 12
- Add 2 to the number before each gap. That gives the missing number.Gap 3: 4 + 2 = 6
Gap 5: 8 + 2 = 10 - Write the missing numbers. 6, 10
Check. Count in 2s all the way along the list. Every number fits. ✓
Watch out. Check the numbers after the gap too. They should still go up in the same jump.
Method. Count in 5s. Each number is 5 more than the one before it.
- Look at the numbers before and after each gap. The jump is the same every time.5, ?, 15, 20, ?, 30
- Add 5 to the number before each gap. That gives the missing number.Gap 2: 5 + 5 = 10
Gap 5: 20 + 5 = 25 - Write the missing numbers. 10, 25
Check. Count in 5s all the way along the list. Every number fits. ✓
Watch out. Check the numbers after the gap too. They should still go up in the same jump.
Method. Count in 10s. Each number is 10 more than the one before it.
- Look at the numbers before and after each gap. The jump is the same every time.10, 20, 30, ?, 50
- Add 10 to the number before each gap. That gives the missing number.Gap 4: 30 + 10 = 40
- Write the missing numbers. 40
Check. Count in 10s all the way along the list. Every number fits. ✓
Watch out. Check the numbers after the gap too. They should still go up in the same jump.
Method. Start at 30. Count on in 5s to find the next 3 numbers.
- Start at 30. Start with the number you are given.30
- Jump on by 5 each time. Each new number is the last one plus the jump.30 + 5 = 35
35 + 5 = 40
40 + 5 = 45 - Write the next numbers. Do not write the start number again.35, 40, 45
Check. Count back in 5s from 45 to 30 to check. ✓
Watch out. Do not write the number you start at. Start with the next one.
Key words. Counting in 2s means jumping on by 2 each time.
Method. Count in 2s. Every jump is the same size: 2.
- Start at 2. Put your finger on the first number.2
- Jump on by 2 each time. Each number is 2 more than the one before.2 + 2 = 4
4 + 2 = 6
6 + 2 = 8
8 + 2 = 10 - Write the numbers. Say them in order, one jump at a time.2, 4, 6, 8, 10
Check. Count back in 2s from 10 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 2 more than the one before.
Key words. Counting in 5s means jumping on by 5 each time.
Method. Count in 5s. Every jump is the same size: 5.
- Start at 5. Put your finger on the first number.5
- Jump on by 5 each time. Each number is 5 more than the one before.5 + 5 = 10
10 + 5 = 15
15 + 5 = 20 - Write the numbers. Say them in order, one jump at a time.5, 10, 15, 20
Check. Count back in 5s from 20 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 5 more than the one before.
Key words. Counting in 10s means jumping on by 10 each time.
Method. Count in 10s. Every jump is the same size: 10.
- Start at 10. Put your finger on the first number.10
- Jump on by 10 each time. Each number is 10 more than the one before.10 + 10 = 20
20 + 10 = 30
30 + 10 = 40
40 + 10 = 50
50 + 10 = 60 - Write the numbers. Say them in order, one jump at a time.10, 20, 30, 40, 50, 60
Check. Count back in 10s from 60 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 10 more than the one before.
Key words. Counting in 5s means jumping on by 5 each time.
Method. Count in 5s. Every jump is the same size: 5.
- Start at 5. Put your finger on the first number.5
- Jump on by 5 each time. Each number is 5 more than the one before.5 + 5 = 10
10 + 5 = 15
15 + 5 = 20 - Write the numbers. Say them in order, one jump at a time.5, 10, 15, 20
Check. Count back in 5s from 20 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 5 more than the one before.
Key words. Counting in 10s means jumping on by 10 each time.
Method. Count in 10s. Every jump is the same size: 10.
- Start at 10. Put your finger on the first number.10
- Jump on by 10 each time. Each number is 10 more than the one before.10 + 10 = 20
20 + 10 = 30 - Write the numbers. Say them in order, one jump at a time.10, 20, 30
Check. Count back in 10s from 30 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 10 more than the one before.
Key words. Counting in 5s means jumping on by 5 each time.
Method. Count in 5s. Every jump is the same size: 5.
- Start at 5. Put your finger on the first number.5
- Jump on by 5 each time. Each number is 5 more than the one before.5 + 5 = 10
10 + 5 = 15
15 + 5 = 20 - Write the numbers. Say them in order, one jump at a time.5, 10, 15, 20
Check. Count back in 5s from 20 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 5 more than the one before.
Key words. Counting in 2s means jumping on by 2 each time.
Method. Count in 2s. Every jump is the same size: 2.
- Start at 2. Put your finger on the first number.2
- Jump on by 2 each time. Each number is 2 more than the one before.2 + 2 = 4
4 + 2 = 6
6 + 2 = 8
8 + 2 = 10
10 + 2 = 12 - Write the numbers. Say them in order, one jump at a time.2, 4, 6, 8, 10, 12
Check. Count back in 2s from 12 to check. ✓
Watch out. Keep the same jump all the way. Every number must be 2 more than the one before.
Method. Write the numbers in the 5s and the 10s. Then check each 10 is in the 5s.
- Write the 5s. Count in 5s.5, 10, 15, 20, 25, 30
- Write the 10s. Count in 10s.10, 20, 30, 40
- Check each 10 is in the 5s. 10, 20 and 30 are all in the list of 5s.10 is in the 5s, 20 is in the 5s, 30 is in the 5s
- Write the answer. Yes. Every number in the 10s is in the 5s.
Check. Count in 5s to 40: 5, 10, 15, 20, 25, 30, 35, 40. 40 is in the list too. ✓
Watch out. Every jump of 10 is two jumps of 5, so the 10s always land on the 5s.
Method. Count in 2s and see if 7 comes up.
- Count in 2s. Start at 2 and jump on by 2.2, 4, 6, 8
- Look for 7. The numbers jump from 6 to 8. 7 is skipped.6, then 8. No 7.
- Write the answer. No. 7 is not in the 2s.
Check. Every number in the 2s is even. 7 is odd, so it is not there. ✓
Watch out. Do not guess. Count in 2s and see which numbers come up.