How to Round Off Decimals

Read,3 minutes

Rounding a decimal means replacing it with a nearby number that is easier to use. First identify the place you are rounding to: whole number, tenth, hundredth, thousandth, or another place.

Look one digit to the right of the rounding place. If that digit is \(0,1,2,3,\) or \(4\), keep the rounding digit the same. If it is \(5,6,7,8,\) or \(9\), increase the rounding digit by \(1\). Then replace all digits to the right with zeros or remove them if they are after the decimal point.

Examples

Example 1: Round \(12.463\) to the nearest hundredth. The hundredths digit is \(6\), and the next digit is \(3\). Keep \(6\), so \(12.463\approx 12.46\).

Example 2: Round \(4.987\) to the nearest tenth. The tenths digit is \(9\), and the next digit is \(8\). Rounding up carries through the \(9\), so \(4.987\approx 5.0\).

Practice Exercises

1) Round \(4.6\) to the nearest whole number.

2) Round \(8.24\) to the nearest tenth.

3) Round \(3.145\) to the nearest hundredth.

4) Round \(0.074\) to the nearest hundredth.

5) Round \(12.995\) to the nearest hundredth.

6) Round \(6.249\) to the nearest tenth.

7) Round \(45.050\) to the nearest whole number.

8) Round \(0.999\) to the nearest tenth.

9) Round \(18.375\) to the nearest hundredth.

10) Round \(7.4449\) to the nearest thousandth.

11) Round \(203.506\) to the nearest whole number.

12) Round \(9.995\) to the nearest hundredth.

13) Round \(0.00486\) to the nearest thousandth.

14) Round \(56.789\) to the nearest ten.

15) A length is \(14.267\) cm. Round it to the nearest tenth of a centimeter.

16) Round \(2.3499\) to the nearest hundredth.

17) Round \(99.95\) to the nearest whole number.

18) Round \(5.5555\) to the nearest thousandth.

19) Round \(0.00049\) to the nearest thousandth.

20) Round \(678.9875\) to the nearest hundredth.

Answers

1) The rounding place is the ones place. The tenths digit is \(6\), which is \(5\) or more, so increase \(4\) to \(5\). Answer: \(5\).

2) The rounding place is the tenths digit \(2\). The next digit is \(4\), which is less than \(5\), so keep the \(2\). Answer: \(8.2\).

3) The rounding place is the hundredths digit \(4\). The next digit is \(5\), so increase \(4\) to \(5\). Answer: \(3.15\).

4) The rounding place is the hundredths digit \(7\). The next digit is \(4\), so keep \(7\). Answer: \(0.07\).

5) The rounding place is the hundredths digit \(9\). The next digit is \(5\), so round up. The hundredths \(9\) becomes \(10\) hundredths, carrying to the tenths: \(12.995\approx 13.00\). Answer: \(13.00\).

6) The rounding place is the tenths digit \(2\). The next digit is \(4\), so keep \(2\). Answer: \(6.2\).

7) The rounding place is the ones digit \(5\). The next digit is \(0\), so keep the ones digit. Answer: \(45\).

8) The rounding place is the tenths digit \(9\). The next digit is \(9\), so round up. \(0.999\) to the nearest tenth is \(1.0\).

9) The rounding place is the hundredths digit \(7\). The next digit is \(5\), so increase \(7\) to \(8\). Answer: \(18.38\).

10) The rounding place is the thousandths digit \(4\). The next digit is \(9\), so increase \(4\) to \(5\). Answer: \(7.445\).

11) The rounding place is the ones digit \(3\). The next digit is \(5\), so increase \(203\) to \(204\). Answer: \(204\).

12) The rounding place is the hundredths digit \(9\). The next digit is \(5\), so round up. Carrying changes \(9.99\) to \(10.00\). Answer: \(10.00\).

13) The rounding place is the thousandths digit \(4\). The next digit is \(8\), so increase \(4\) to \(5\). Answer: \(0.005\).

14) The rounding place is the tens digit \(5\). The ones digit is \(6\), so increase \(5\) tens to \(6\) tens. Answer: \(60\).

15) The rounding place is the tenths digit \(2\). The next digit is \(6\), so increase \(2\) to \(3\). Answer: \(14.3\) cm.

16) The rounding place is the hundredths digit \(4\). The next digit is \(9\), so increase \(4\) to \(5\). Answer: \(2.35\).

17) The rounding place is the ones digit \(9\). The tenths digit is \(9\), so round up. \(99.95\) becomes \(100\) to the nearest whole number.

18) The rounding place is the thousandths digit \(5\). The next digit is \(5\), so increase the thousandths digit by \(1\). Answer: \(5.556\).

19) The rounding place is the thousandths digit. Write \(0.00049\) as \(0.00049\): the thousandths digit is \(0\), and the next digit is \(4\), so keep \(0\). Answer: \(0.000\).

20) The rounding place is the hundredths digit \(8\). The next digit is \(7\), so increase \(8\) to \(9\). Answer: \(678.99\).

Free printable Worksheets