Reception Maths: Counting past 20
Part of the Reception Maths numbers to 20 chapter. Chapter overview · whole chapter on one page
Counting past 20
The counting does not stop at 20. Keep going: 21, 22, 23 and on.
Look at the pattern. The tens digit stays 2 from 20 to 29. Then 30 starts the next group of tens.
Key ideas
- After 20 comes 21, then 22, and so on.
- From 20 to 29 the tens digit stays 2.
- After 29 comes 30.
Method. Find 22 on the number track. The number after it is the answer.
- Find 22. Put your finger on it.22
- Move one box to the right. Each box is one more or one less.22 + 1 = 23
- Write the answer. 23
Check. Check it: 23 − 1 = 22. ✓
Watch out. Move one box only. Do not write the number you started with.
Method. Start at 24 and count on to 27. Each number is one more than the one before.
- Start at 24. Say the first number.24
- Count on to 27. Say each number, one more each time.24, 25, 26, 27
- Write the numbers. Write them in order.24, 25, 26, 27
Check. Count back from 27 to 24. You say the same numbers in reverse. ✓
Watch out. Do not skip a number. Check each one is one more than the last.
Method. Start at 30 and count back to 27. Each number is one less than the one before.
- Start at 30. Start with the biggest number.30
- Count back to 27. Each number is one less.30, 29, 28, 27
- Write the numbers. Include the first and last numbers.30, 29, 28, 27
Check. Count on from 27 to 30 to check. ✓
Watch out. Count back one at a time. Do not jump over a number.
Watch out
Watch out: after 29 comes 30, not 210. Thirty is one new ten.
Exam tip
Grown-up tip. Count past 20 on a stair or a shopping list. Stop at each ten and say the new word: twenty, thirty.
Exercise 2E Counting past 20
Non-calculatorMethod. Find 20 on the number track. The number after it is the answer.
- Find 20. Put your finger on it.20
- Move one box to the right. Each box is one more or one less.20 + 1 = 21
- Write the answer. 21
Check. Check it: 21 − 1 = 20. ✓
Watch out. Move one box only. Do not write the number you started with.
Method. Find 24 on the number track. The number after it is the answer.
- Find 24. Put your finger on it.24
- Move one box to the right. Each box is one more or one less.24 + 1 = 25
- Write the answer. 25
Check. Check it: 25 − 1 = 24. ✓
Watch out. Move one box only. Do not write the number you started with.
Method. Find 29 on the number track. The number after it is the answer.
- Find 29. Put your finger on it.29
- Move one box to the right. Each box is one more or one less.29 + 1 = 30
- Write the answer. 30
Check. Check it: 30 − 1 = 29. ✓
Watch out. Move one box only. Do not write the number you started with.
Method. Start at 20 and count on to 25. Each number is one more than the one before.
- Start at 20. Say the first number.20
- Count on to 25. Say each number, one more each time.20, 21, 22, 23, 24, 25
- Write the numbers. Write them in order.20, 21, 22, 23, 24, 25
Check. Count back from 25 to 20. You say the same numbers in reverse. ✓
Watch out. Do not skip a number. Check each one is one more than the last.
Method. Start at 30 and count back to 26. Each number is one less than the one before.
- Start at 30. Start with the biggest number.30
- Count back to 26. Each number is one less.30, 29, 28, 27, 26
- Write the numbers. Include the first and last numbers.30, 29, 28, 27, 26
Check. Count on from 26 to 30 to check. ✓
Watch out. Count back one at a time. Do not jump over a number.
Method. Each number is one more than the number before. Use the numbers you can see to find the gaps.
- Look at the numbers around each gap. Counting on means each number is one more.21, ?, 23
- Add one to the number before each gap. That gives the missing number.Gap 2: 21 + 1 = 22
- Write the missing numbers. 22
Check. Read the whole line again. Every number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Each number is one more than the number before. Use the numbers you can see to find the gaps.
- Look at the numbers around each gap. Counting on means each number is one more.27, ?, 29
- Add one to the number before each gap. That gives the missing number.Gap 2: 27 + 1 = 28
- Write the missing numbers. 28
Check. Read the whole line again. Every number is one more than the one before. ✓
Watch out. Check the numbers after the gap too. They should still go up by one.
Method. Say the number, then write its name in words.
- Look at the numeral. Find it on the number list.21
- Find its name. Every number has one name.21 = twenty-one
- Write the word. Write each letter in order.twenty-one
Check. Read the word back. It has the same number of things as 21. ✓
Watch out. Check the spelling. Thirteen, fourteen and fifteen are different words.
Method. Read the whole number word. Then find it on the number list.
- Read the word. Read every part, including the second half of a long word.“twenty-five”
- Find the word on the list. Each word matches one number.twenty-five = 25
- Write the numeral. A numeral uses digits.25
Check. Count 25 things in your head, then check the numeral. ✓
Watch out. Look at the whole word. Thirteen and thirty look alike but are different.
Method. Start at 20. Count on one at a time to 25. Then count how many numbers came after 20.
- Start at 20. We start at 20.20
- Count on to 25. Say each number after 20.21, 22, 23, 24, 25
- Count the numbers after 20. Touch each number once.1, 2, 3, 4, 5
- Write the answer. 5
Check. Count back from 25 to 20: 5 numbers. ✓
Watch out. Do not count 20 itself. Start counting after it.
Method. Look at the first digit of each number from 20 to 29.
- Look at 20 to 29. Each number has 2 tens.20, 21, ... 29
- Check the first digit. The first digit is 2 for all of them.2 tens
- Write the answer. Yes. The tens digit stays 2 until 29.
Check. The ones change, but the tens stay the same. ✓
Watch out. Only the ones change in the twenties.
Method. Think about the ones first, then what happens after 9 ones.
- Look at 29. It has 2 tens and 9 ones.2 tens and 9 ones
- Add one more. Nine ones and one more make one ten.9 + 1 = 10
- Write the answer. Now there are 3 tens.Accept any answer: 29 has 2 tens and 9 ones, so one more is 3 tens, which is 30.
Check. Count 29, 30. Thirty is three tens. ✓
Watch out. Ten ones make a new ten.