Understand decimals: FAQ

A fraction is a way of expressing a part of a whole, using two numbers separated by a slash. For example, ${\displaystyle \frac{1}{2}}$‍ means "one half." A decimal is another way of expressing a part of a whole, using a decimal point. For example, $0.5$‍ also means "one half."

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Grids and number lines can help us visualize decimals and fractions, which can make them easier to understand. By seeing how they're laid out, we can better compare them and see how they relate to one another.

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To write a fraction as a decimal, divide the top number (the numerator) by the bottom number (the denominator). For example, ${\displaystyle \frac{3}{4}}$‍ can be written as $0.75$‍.

To write a decimal as a fraction, count the number of places after the decimal point. Write the decimal as the numerator, and put a 1 as the denominator, followed by as many zeroes as there are places after the decimal point. For example, $0.37$‍ can be written as ${\displaystyle \frac{37}{100}}$‍.

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To compare two decimals, we can look at the whole numbers before the decimal point. If one of these is larger, we know that number is larger overall. If the whole numbers are the same, we can compare the decimal digits, starting on the left. In cases where one decimal has more digits than the other, you can add zeroes to the end of the shorter decimal to make the comparison easier.

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Decimals and fractions are used all over the place! For example, they're used in cooking and baking (i.e. ${\displaystyle \frac{1}{2}}$‍ teaspoon), in sports (i.e. batting average of $0.250$‍), and in finance (i.e. a $2.5\mathrm{\%}$‍ interest rate).