5th Grade Math: Rounding Decimals to the Nearest Thousandth

Rounding Decimals in 5th Grade

Your 5th grade math curriculum will feature lessons on rounding decimals, including the more advanced skill of rounding to the nearest thousandth. Before we explain how to do this, though, it will be helpful to review decimal places.

Decimal Place Values

Decimals are the digits to the right of a number's decimal point. Since they always express quantities between zero and one, most decimals can also be written as fractions. In fact, each decimal place, or digit, represents a fraction of a base-ten number.

The first digit to the right of the decimal point is in the tenths place, which means it can be written as a fraction over ten (e.g., 0.1 = 1/10 and 0.7 = 7/10). If the decimal extends to the hundredths place, which is the next digit to the right of the tenths place, then it can be written as a fraction over 100. For example, 0.23 = 23/100 and 0.99 = 99/100.

The third place to the right of the decimal point is the thousandths place, and the fourth place to the right is the 10-thousandths place. Each decimal place value is equal to 1/10 of the place to its left.

Rounding to the Thousandths Place

To round a decimal, start by identifying the place you're being asked to round to. This tells you how many decimal places your final answer should have. If you're rounding to the nearest thousandth, your answer will have three decimal places (the tenths, hundredths and thousandths places).

The next step is to decide whether to round your decimal up or down. You'll determine this by looking at the number that's immediately to the right of the decimal place that you're rounding to. If you're rounding to the nearest thousandth, you'll look at the number in the 10-thousandths place.

If that number is five or greater, you'll round the number in the thousandths place up by adding one to it. If that number is less than five, you'll keep the number in the thousandths place the same. In either case, you'll drop the number in the 10-thousandths place so that your answer only has three decimal places.

For example, 0.1234 would be rounded to 0.123 because four is less than five, while 0.1235 would be rounded to 0.124 because the digit in the 10-thousandths place of the original decimal is five or greater. Here are a few more examples of how to round to the nearest thousandth:

0.0068 rounds to 0.007

0.0064 rounds to 0.006

4.5679 rounds to 4.568

4.5673 rounds to 4.567