Use hundreds, tens and ones

What you will learn

• Use hundreds, tens and ones

Models used: number sentences, stories, diagrams.

Before you start

• Count and represent numbers to 1000

Every digit has a job

The counters are sorted into columns. Each column tells us the size of its units.

1. 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.

   Three tens and three ones both use the digit three, but they describe different amounts. Zero keeps an empty column in the correct position.

2. 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.

3. 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.

   302

   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.

4. 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.

   300 + 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.

Worked example: A new example, together

What is the value in the ones column of 339?

1. The number at the top of each column is the value of one counter in that column.

   Read the column name, then the digit. Join the place values to check the number.

   A digit counts units of its place value.

2. 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 339?

   9

3. 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.

4. The number at the top of each column is the value of one counter in that column.

   The digit is 9.

   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.

5. The number at the top of each column is the value of one counter in that column.

   9 × 1 = 9.

   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.

6. 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 339.

   We found 9. 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 hundreds, tens and ones
• connect a numeral or number name with its place-value groups
• 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.