Estimating and Calculating

If there is a coat with a price tag reading "$89", you would say that this coat costs around $90. 

This is because $89 is closer to $90 than it is to $80, so $90 is a reasonable approximation. 

$89 has been rounded up to $90. 

Similarly, if the coat cost $82, you would say that it costs around $80 because it is closer to $80 than it is to $90. 

Both of these numbers have been rounded to the nearest 10. 

Rounding to the nearest 10 means rounding to 10, 20, 30, 40, etc. 

The number will end in 0. 

The process of rounding to the nearest 10 is summarised below. 

A number ending in 1,2,3 or 4 or less is rounded down; a number ending in 5, 6, 7, 8 or 9 is rounded up.