Primary 1 maths · Whole numbers · About 8 minutes
Count and represent numbers to 100
Say how many tens and how many ones the number has.
Start the interactive lesson →Open practice activity
What you will learn
- Count and represent numbers to 100
Models used: number sentences, stories, diagrams.
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.
The 4 sits in the tens place, so it counts 4 groups of ten: 40. The 7 counts single ones. Together they make 47.
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 ones column of 55?
The number at the top of each column is the value of one counter in that column.
Say how many tens and how many ones the number has.
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 ones 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 ones column of 55?
5
The number at the top of each column is the value of one counter in that column.
Locate the ones 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.
The number at the top of each column is the value of one counter in that column.
The digit is 5.
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.
5 × 1 = 5.
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 55.
We found 5. A digit counts units of its place value.
Common mistakes to discuss
- Counting the marks, not the groups. One ten-rod stands for ten ones. A picture of 2 rods and 6 singles shows 26, not 8 objects.
Check your understanding
- Count and represent numbers to 100
- read a number to 100 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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