Primary 4 maths · Decimals · About 12 minutes
Tenths, hundredths and thousandths
Read the value of each digit in a decimal
Start the interactive lesson →Open practice activity
What you will learn
- Read the value of each digit in a decimal
- Write a decimal from its place-value parts
- Convert tenths and hundredths between fractions and decimals
- Compare decimals by place value
Models used: place-value charts, hundred grids, number sentences, stories.
Before you start
Every place is ten times smaller
What does each digit in 0.347 tell us about the amount?
Read the place heading before the digit. A counter in a different column has a different value.
Start with three tenths. The 3 belongs in the tenths column because it counts pieces of size one tenth.
0.3 = 3 tenths
Ones0Tenths30.3 = 3 tenths
Read the place heading before the digit. A counter in a different column has a different value.
Split a tenth into ten hundredths. Add four hundredths; the three tenths stay where they are.
0.34 = 0.3 + 0.04
Ones0Tenths3Hundredths40.34 = 3 tenths + 4 hundredths
Read the place heading before the digit. A counter in a different column has a different value.
Split a hundredth into ten thousandths. Add seven thousandths in the next column.
0.347 = 0.3 + 0.04 + 0.007
Ones0Tenths3Hundredths4Thousandths70.347 = 3 tenths + 4 hundredths + 7 thousandths
Read the place heading before the digit. A counter in a different column has a different value.
A digit tells us how many; its column tells us the size of each piece. Here the 7 means seven thousandths, not seven ones.
Value of 7: 0.007
Ones0Tenths3Hundredths4Thousandths70.347 = 3 tenths + 4 hundredths + 7 thousandths
Why does 0.8 equal 0.80?
8 tenths and 80 hundredths shade exactly the same part of the square: each tenth is ten hundredths. Writing an extra zero on the right adds no value, it only says the amount to a finer level of detail.
80/100 = 0.8 = 80%
Worked example
What is the value of the 4 in 3.427?
Put the number into the chart.
Ones3Tenths4Hundredths2Thousandths73.427 = 3 ones + 4 tenths + 2 hundredths + 7 thousandths
Which column is the 4 in?
The 4 is in the…
tenths column
A digit in the tenths column is worth that many tenths.
4 tenths = 4 ÷ 10
What is the value of the 4?
0.4
So the 4 is worth 0.4, not 4.
3.427 = 3 + 0.4 + 0.02 + 0.007
Common mistakes to discuss
- Reading decimals as whole numbers. 0.75 is not bigger than 0.8 because 75 > 8. Compare tenths first: 0.8 has 8 tenths, 0.75 has 7.
- Confusing a digit with its value. The 4 in 3.427 is worth 4 tenths, not 4. Its column decides its value.
Check your understanding
- say what the 4 is worth in 3.427
- write 4 tenths and 3 hundredths as 0.43
- change 7/10 and 35/100 into decimals
- explain why 0.8 is bigger than 0.75
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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