Rounding decimals

key notes :

Just like with whole numbers, you can round decimal numbers. When you round a decimal number, you switch to a nearby number that stops at a specific decimal place. Rounding a number makes it easier to work with. For example, if Bob bought a watermelon that weighed 15.37 pounds, you could round to the tenths place and say that’s about 15.4 pounds.

How do you round a decimal?

Let’s try it! To start, let’s round 2.8 to the nearest whole number. You can look at a number line and see that 3 is the nearest whole number.

You can also round without looking at a number line. Just follow these steps:

1. First, find the digit in the place you are rounding to.
2. Look at the digit one place to the right.
3. If the digit is less than 5, round down. If the digit is 5 or greater, round up.

Let’s go back and try this with 2.8. First, find the digit in the ones place.
2.8
Now, look one place to the right.
2.8
Since 8 is greater than 5, round up.
2.8 → 3
So, 2.8 rounded to the nearest whole number is 3.

Another example

Next, let’s try rounding 29.34 to the nearest tenth.
First, find the digit in the tenths place.
29.34
Now, look one place to the right.
29.34
Since the digit 4 is less than 5, round down.
29.34 → 29.3
29.34 rounded to the nearest tenth is 29.3.

One more example

Next, let’s try rounding 591.625 to the nearest hundredth.
First, find the digit in the hundredths place.
591.625
Now, look one place to the right.
591.625
Since the digit 5 is 5 or greater, round up.
591.625 → 591.63
591.625 rounded to the nearest hundredth is 591.63.

Rounding money

You can round money numbers, too! For example, what is $7.30 rounded to the nearest dollar?
First, find the digit in the ones place.
$7.30
Now, look one place to the right.
$7.30
Since the digit is less than 5, round down.
$7.30 → $7.00
$7.30 rounded to the nearest dollar is $7.00.

Learn with an example

Let’s practice!