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Part 2:
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Basic Arithmetic Skills |
| Rounding Off What do we do if answers don't work out 'nicely'? Suppose you have two paint suppliers whose prices you want to compare. One sells a 5 litre can of paint for £7.99 and the other a 7.5 litre tin of the same paint for £10.49. Which offers the better buy? You could find the answer in several ways, but one way would be to find the cost per litre for each tin: divide the cost by the number of litres. Tin A: 7.99 ÷ 5 = 1.598 Tin B: 10.49 ÷ 7.5 = 1.3986666667 For a litre of paint Tin A costs nearly £1.60 and Tin B costs nearly £1.40 so Tin B is the best buy. What we have done here is rounded off our calculator display to the nearest penny. Rounding off is a very important skill and it has to be done accurately. When you round off a number, you do not change its size. You simply show less detail. |
