Rounding Decimals

Rounding a number means making a number simpler but keeping its value closer to the original number. The rounded number is less accurate but easy to use. Rounding decimals is similar to rounding whole numbers.

Rules for Rounding Numbers

We decide which is the last digit in the number to keep.

We keep the digit same if the next digit is less than 5 (i.e., 0, 1, 2, 3, or 4). This is called rounding down.

We increase the digit by 1 if the next digit is 5 or more (i.e., 5, 6, 7, 8, or 9). This is called rounding up.

Example 1:

Round 63 to the nearest 10

Solution:

We keep the "6" (it is in the tens place)

The next digit is "3" which is less than 5, so we keep "6" and drop 3.

So, here 63 is getting rounded down to 60.

Example 2:

Round 38 to the nearest 10

Solution:

We take the 3 (it is in the tens place)

The next digit is "8" which is more than 5, so we add 1 to 3 to get 4 and drop 8. So, here 38 is getting rounded up to 40.

Round 23.76 to the nearest tenth.

Solution

Step 1:

The rounding digit here is the tenths digit which is 7.

Step 2:

We find that the digit to the right of 7 is 6 which is more than 5.
So we add a 1 to 7 and it becomes 8 and 6 is dropped.

Step 3:

So 23.76 rounded to nearest tenth is 23.8

Round 76.5648 to the nearest hundredth.

Solution

Step 1:

The rounding digit here is the hundredths digit which is 6.

Step 2:

We find that the digit to the right of 6 is 4 which is less than 5.
So we keep 6 and drop the digits after 6.

Step 3:

So 76.5648 rounded to nearest hundredth is 76.56