Why do we round numbers?

Answer 1

We round numbers when:

• an approximation is needed; or
• the numbers become too large and complicated; or
• the removed digits make little difference to the value
• keeping the extra digits could mean the result would be more accurate than the original figure.

This third is dependent upon the size of the number, for example:

• talking about a national debt to the nearest pound or dollar does not make much sense as £1 or $1 is going to make little difference when the national debt is in terms of billions - it would be usual to round to the nearest hundredth of a billion (ie 2 decimal places);
• when doing calculations with Ï€, it is often accurate enough to work with a value for pi of 3.1416 or even just 3.14