Decimals as tenths and hundredths

Read tenths and hundredths as decimals, change fractions with a denominator of 10 or 100 into decimals, and compare decimals to hundredths.

Tenths and hundredths

Cut a whole into 10 equal parts and each part is one tenth. Cut it into 100 equal parts and each part is one hundredth. 10 hundredths make 1 tenth.

The decimal point separates the whole numbers from the parts. The first place after it is tenths and the second is hundredths. 0.34 is 3 tenths and 4 hundredths, which is 34 hundredths.

2.07 is 2 ones, 0 tenths and 7 hundredths.

From fraction to decimal

A fraction with a denominator of 10 or 100 is easy to write as a decimal: $\frac{7}{10}$ = 0.7, and $\frac{29}{100}$ = 0.29.

To add tenths and hundredths, first write the tenths as hundredths: $\frac{3}{10}$ = $\frac{30}{100}$, so $\frac{3}{10}$ + $\frac{4}{100}$ = $\frac{34}{100}$ = 0.34.

Comparing decimals

To compare decimals, line up the decimal points and compare place by place from the left. In 0.47 and 0.5 the tenths are 4 and 5, so 0.5 is greater, even though 47 looks bigger than 5.

Money uses hundredths: $3.45 is 3 dollars and 45 cents, and a cent is one hundredth of a dollar.

Try it yourself

Work each one on paper first, then open the answer to check.

1. Write $\frac{9}{10}$ as a decimal.

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   0.9.

2. Write $\frac{45}{100}$ as a decimal.

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   0.45.

3. Write 0.03 as a fraction.

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   $\frac{3}{100}$

4. Which is greater, 0.3 or 0.29?

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   0.3. It is 30 hundredths.

5. What is $\frac{5}{10}$ + $\frac{20}{100}$? Give a decimal.

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   0.7. $\frac{50}{100}$ + $\frac{20}{100}$ = $\frac{70}{100}$.