Primary 1 maths · Whole numbers · About 8 minutes
Use tens and ones
Count each ten as 10, then count the ones.
Start the interactive lesson →Practise: Tens & ones workshop
What you will learn
- Use tens and ones
Models used: number sentences, stories, diagrams.
Before you start
Every digit has a job
The counters are sorted into columns. Each column tells us the size of its units.
The number at the top of each column is the value of one counter in that column.
The counters are sorted into columns. Each column tells us the size of its units.
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
The number at the top of each column is the value of one counter in that column.
Look at the left column. Its digit counts the biggest units in this number.
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
The number at the top of each column is the value of one counter in that column.
Now read the value of every column. A zero keeps an empty place ready.
32
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
The number at the top of each column is the value of one counter in that column.
Put the values together. These are different ways to describe the very same number.
30 + 2
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
What did the picture help us see?
Put the values together. These are different ways to describe the very same number.
Worked example: A new example, together
What is the value in the tens column of 88?
The number at the top of each column is the value of one counter in that column.
Count each ten as 10, then count the ones.
A digit counts units of its place value.
The number at the top of each column is the value of one counter in that column.
Locate the tens column.
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
What is the value in the tens column of 88?
80
The number at the top of each column is the value of one counter in that column.
The digit is 8.
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
The number at the top of each column is the value of one counter in that column.
8 × 10 = 80.
A digit tells us how many units there are. Its position tells us what size those units are; that is why a zero can matter.
The number at the top of each column is the value of one counter in that column.
Check the result against the question we started with.
Adding the place values rebuilds 88.
We found 80. A digit counts units of its place value.
Common mistakes to discuss
- The digit is the value. A digit counts units of its own column. The 5 in 52 represents 5 tens, which is 50, not 5.
Check your understanding
- Use tens and ones
- read a number as tens and ones
- check the answer against the original quantities and units
Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.
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