Decimal Rounding

Decimal Rounding:

To do decimal rounding:

  • Figure out the place value to be rounded to... (ex: tenths, hundredths, thousandths ...)
  • Round the original number by counting in increments of the place value specified, in a manner that the count surrounds the number being rounded.
    (ex: for rounding 0.23 to tenths, count 0.1, 0.2, [0.23], 0.3, 0.4.)
  • Decide what number in your counted list is closest to the original number.
    (ex: 0.2 = 0.20, 0.3 = 0.30... decide if 0.23 is closer to 0.30 or 0.20)

To round, you have the ability to do the following ....

Given the following following statements, identify the place value we will round to ...

  1. Round 0.762 to the nearest tenth ... Tenth (10th)
  2. Round 0.821 to the nearest hundredth ... Hundredth (100th)
  3. Round 1.2543 to the nearest tenth... Tenth (10th)
  4. Round 53.1239 to the nearest thousandth... Thousandth (1000th)

Counting in increments of the place value ...

Given the following following statements, Count around the given number by the specified place value ...

  • Round 0.768 to the nearest tenth ... 0.6,  0.7,  0.768 0.8,  0.9
  • Round 0.821 to the nearest hundredth... 0.81,  0.82,  0.821 0.83,  0.84, 
  • Round 1.2743 to the nearest tenth... 1.1,  1.2,  1.2743 1.3,  1.4
  • Round 53.1234 to the nearest thousandth... 53.122,  53.123,  53.1234 53.124,  53.125

The following is an example of Rounding to a decimal position.

Given a request to round 0.2344 to the nearest hundredth (100th).

  • Identify the place value you are rounding to ... Rounding to place value 100th
  • Count past and surround the given number by counting by increments of the place value. 0.22, 0.23, 0.2344 0.24, 0.25
  • Decide which of the counted numbers is closest to the given number.Its closest to 0.2344 is closest to 0.23 because 0.2344 is closer to 0.2340 than to 0.2350

Therefore, 0.2344 rounded to the the hundredths position is 0.23

The following is an example of Rounding to a decimal position.

Given a request to round 0.53721 to the nearest hundredth (100th).

  • Identify the place value you are rounding to ... Rounding to place value 100th
  • Count past and surround the given number by counting by increments of the place value. 0.534, 0.535, 0.53591 0.536, 0.537
  • Decide which of the counted numbers is closest to the given number.Its closest to 0.53591 is closest to 0.536 because 0.53591 is closer to 0.53600 than to 0.53500

Therefore, 0.53591 rounded to the the hundredths position is 0.536

The following is an example of Rounding to a decimal position.

Given a request to round 0.1275 to the nearest hundredth (100th).

  • Identify the place value you are rounding to ... Rounding to place value 100th
  • Count past and surround the given number by counting by increments of the place value. 0.126, 0.127, 0.1275 0.128, 0.129
  • Decide which of the counted numbers is closest to the given number.Its closest to 0.1275 is closest to 0.128 because 0.0.1275 is closer to 0.1280 than to 0.1270

Therefore, 0.1275 rounded to the the hundredths position is 0.128

Check Your Understanding

What is the place value mentioned in the following request to round?

  1. Round to the nearest hundredths
  2. Round to the nearest thousandths
  3. Round to the nearest ten-thousandths

Can you count by increments of place values? Think an answer then look at an example of one possible answer ... 

  1. Count by ten-thousandths.
  2. Count by tenths.
  3. Count by thousandths.

Why are the following statements true??

  1. 0.7 is less than 0.71  and 0.71 is less than 0.8
  2. 0.82 is less than 0.821 and 0.821 is less than 0.83
  3. 0.1 is less than 0.15 and 0.15 is less than 0.2
  4. 0.78 is less than 0.78999 and 0.78999 is less than 0.79

Why are the following statements true??

  1. 0.7  and 0.8 surround .78
  2. 0.97 and 0.98 surround 0.972
  3. 0.854 and 0.855 surround 0.8545
  4. 1.4 and 1.5 surround 1.41

Why are the following statements true??

  1. 0.78 is closer to 0.8 than to 0.7
  2. 0.972 is closer to 0.97 than to 0.98
  3. 0.8545 is closer to 0.855 than to 0.854
  4. 1.41 is closer to 1.4 than to 1.5 

Do some interactive practice

  1. Enter a number between 0 and 999.9999.
  2. Enter a place value to round to .... 10ths, 100ths, 1000ths
  3. Figure out what you believe the answer should be.
  4. Click the button "Check" and check your answer.