Step-by-step Maths Level 2: Numbers from 20 to 100
Part of the Step-by-step Maths Level 2 counting to 100 chapter. Chapter overview · whole chapter on one page
Numbers from 20 to 100
Numbers from 20 to 100 have a tens part and a ones part.
The tens word tells you the tens digit. For example, forty is 4 tens, so it is 40.
Key ideas
- The tens digit is written first.
- Twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety.
- A hyphen joins the tens word and the ones word, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.sixty = 6 tens
- Find the ones word. The ones word tells us the ones digit.three = 3
- Write the numeral. Tens digit first, then ones digit.63
Check. Say 63 as a number name to check: sixty-three.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.2 tens = twenty
- Find the ones part. The ones digit gives the last word.9 ones: nine ones
- Write the name. Put a hyphen between the tens word and the ones word.twenty-nine
Check. Read the name back: twenty-nine is 29.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.8 tens = eighty
- Find the ones part. The ones digit gives the last word.0 ones: no ones, so there is no hyphen
- Write the name. Put a hyphen between the tens word and the ones word.eighty
Check. Read the name back: eighty is 80.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Watch out
Watch out. Thirteen is 13, but thirty is 30. Check the tens digit first.
Exam tip
Grown-up tip. Say the number names out loud. Count in tens, then add the ones. Write the number as a numeral.
Exercise 1D Practice: numerals and words
Non-calculatorMethod. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.twenty = 2 tens
- Find the ones word. The ones word tells us the ones digit.two = 2
- Write the numeral. Tens digit first, then ones digit.22
Check. Say 22 as a number name to check: twenty-two.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.3 tens = thirty
- Find the ones part. The ones digit gives the last word.5 ones: five ones
- Write the name. Put a hyphen between the tens word and the ones word.thirty-five
Check. Read the name back: thirty-five is 35.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.twenty = 2 tens
- Find the ones word. The ones word tells us the ones digit.eight = 8
- Write the numeral. Tens digit first, then ones digit.28
Check. Say 28 as a number name to check: twenty-eight.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.3 tens = thirty
- Find the ones part. The ones digit gives the last word.9 ones: nine ones
- Write the name. Put a hyphen between the tens word and the ones word.thirty-nine
Check. Read the name back: thirty-nine is 39.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.seventy = 7 tens
- Find the ones word. The ones word tells us the ones digit.one = 1
- Write the numeral. Tens digit first, then ones digit.71
Check. Say 71 as a number name to check: seventy-one.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.5 tens = fifty
- Find the ones part. The ones digit gives the last word.6 ones: six ones
- Write the name. Put a hyphen between the tens word and the ones word.fifty-six
Check. Read the name back: fifty-six is 56.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.thirty = 3 tens
- Find the ones word. The ones word tells us the ones digit.six = 6
- Write the numeral. Tens digit first, then ones digit.36
Check. Say 36 as a number name to check: thirty-six.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.2 tens = twenty
- Find the ones part. The ones digit gives the last word.1 ones: one ones
- Write the name. Put a hyphen between the tens word and the ones word.twenty-one
Check. Read the name back: twenty-one is 21.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.sixty = 6 tens
- Find the ones word. The ones word tells us the ones digit.two = 2
- Write the numeral. Tens digit first, then ones digit.62
Check. Say 62 as a number name to check: sixty-two.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.6 tens = sixty
- Find the ones part. The ones digit gives the last word.4 ones: four ones
- Write the name. Put a hyphen between the tens word and the ones word.sixty-four
Check. Read the name back: sixty-four is 64.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.twenty = 2 tens
- Find the ones word. The ones word tells us the ones digit.seven = 7
- Write the numeral. Tens digit first, then ones digit.27
Check. Say 27 as a number name to check: twenty-seven.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.4 tens = forty
- Find the ones part. The ones digit gives the last word.4 ones: four ones
- Write the name. Put a hyphen between the tens word and the ones word.forty-four
Check. Read the name back: forty-four is 44.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.eighty = 8 tens
- Find the ones word. The ones word tells us the ones digit.eight = 8
- Write the numeral. Tens digit first, then ones digit.88
Check. Say 88 as a number name to check: eighty-eight.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.6 tens = sixty
- Find the ones part. The ones digit gives the last word.0 ones: no ones, so there is no hyphen
- Write the name. Put a hyphen between the tens word and the ones word.sixty
Check. Read the name back: sixty is 60.
Watch out. Use a hyphen between tens and ones, for example forty-six.
Method. Find the tens first, then the ones.
- Find the tens word. The tens word tells us how many tens.twenty = 2 tens
- Find the ones word. The ones word tells us the ones digit.zero = 0
- Write the numeral. Tens digit first, then ones digit.20
Check. Say 20 as a number name to check: twenty.
Watch out. Write the tens digit first. Seventy-four is 74, not 47.
Method. Say the tens part, then the ones part.
- Find the tens part. The tens digit gives the tens word.5 tens = fifty
- Find the ones part. The ones digit gives the last word.0 ones: no ones, so there is no hyphen
- Write the name. Put a hyphen between the tens word and the ones word.fifty
Check. Read the name back: fifty is 50.
Watch out. Use a hyphen between tens and ones, for example forty-six.