# Rounding

## Rounding

A process that consists of providing a close and simpler value of a number that is known or to be calculated that is less precise but easier to use.

The normal method of rounding a number to a certain position consists of keeping the last digit in this position unchanged if it is followed by a 0, 1, 2, 3 or 4, or increasing the digit by 1 if it is immediately followed by a 5, 6, 7, 8 or 9. This way of rounding numbers corresponds to an approximation by rounding.

It’s important to pay particular attention to negative numbers, which do not work exactly the same way. In the case of a negative number, the last digit in this position remains unchanged if it is followed by a 0, 1, 2, 3, 4 or 5, or the digit is increased by 1 if it is immediately followed by a 6, 7, 8 or 9.

### Example

If rounding a decimal number to the nearest whole, then:

• 34.4 rounded gives 34
• 34.5 rounded gives 35
• 34.6 rounded gives 35
• −34.4 rounded gives −34
• −34.5 rounded gives −34
• −34.6 rounded gives −35

### Educational Note

To solve some problem situations, the context determines how to round them. So, we may have to round them to the nearest greater whole number or to the nearest lesser whole number. This is known as rounding up or rounding down to an approximate value.

If we have to divide 30 bottles into cases that can each contain 12 bottles, then the result of the division of 30 by 12 will give 3, which is rounding up to an approximate value, if we are looking for the number of cases required, or 2 if we are looking for the number of cases that are filled completely.