Round decimals

key notes:

What is Rounding?

Rounding is the process of adjusting a number to a simpler, often more convenient value, while keeping it as close as possible to the original number.

Steps to Round Decimals:

  1. Identify the place value to round to (e.g., tenths, hundredths, thousandths).
  2. Look at the digit in the place value immediately to the right of the place you are rounding to.
  3. Decide how to round:
    • If the digit is 5 or greater, round up by increasing the digit in the place value you are rounding to by 1.
    • If the digit is less than 5, round down by leaving the digit in the place value you are rounding to the same and changing the digits to the right to zero or removing them.

Examples:

  1. Rounding to the nearest tenth:
    • 4.76 → Look at the digit in the hundredths place (6). Since 6 is greater than 5, round up.
      Answer: 4.8
  2. Rounding to the nearest hundredth:
    • 5.387 → Look at the digit in the thousandths place (7). Since 7 is greater than 5, round up.
      Answer: 5.39
  3. Rounding to the nearest whole number:
    • 3.49 → Look at the digit in the tenths place (4). Since 4 is less than 5, round down.
      Answer: 3

Rounding Rules to Remember:

  • Round up if the digit after the place value you’re rounding to is 5 or greater.
  • Round down if the digit after the place value you’re rounding to is less than 5.

Practice Problems:

  1. Round 2.35 to the nearest tenth.
  2. Round 7.618 to the nearest hundredth.
  3. Round 8.91 to the nearest whole number.

Learn with an example

What is 52.8 rounded to the nearest whole number?

First, find the digit in the ones place. This is the place you want to round:

52.8

Now look one place to the right:

52.8

8 is greater than 5, so you will round up. Remove all the digits to the right of the ones place:

52.8 → 52

Now add 1 to the number:

52 → 53

What is 31.8 rounded to the nearest whole number?

First, find the digit in the ones place. This is the place you want to round:

31.8

Now look one place to the right:

31.8

8 is greater than 5, so you will round up. Remove all the digits to the right of the ones place:

31.8 → 31

Now add 1 to the number:

31 → 32

What is 93.3 rounded to the nearest whole number?

First, find the digit in the ones place. This is the place you want to round:

93.3

Now look one place to the right:

93.3

3 is less than 5, so you will round down. Remove all the digits to the right of the ones place:

93.3 → 93

What is 8.2 rounded to the nearest whole number?

First, find the digit in the ones place. This is the place you want to round:

8.2

Now look one place to the right:

8.2

2 is less than 5, so you will round down. Remove all the digits to the right of the ones place:

8.2 → 8

What is 2.5 rounded to the nearest whole number?

First, find the digit in the ones place. This is the place you want to round:

2.5

Now look one place to the right:

2.5

5 is equal to 5, so you will round up. Remove all the digits to the right of the ones place:

2.5 → 2

Now add 1 to the number:

2 → 3

let’s practice: