Percentages 221
So, summarized, to calculate the percentage of 17 to 58, for example,
you would divide 17 by 58 and multiply the answer by 100. Your
calculation would look like this:
17 /^58 × 100 = 1,700/^58 = 29.3
CALCULATING A PERCENTAGE OF A GIVEN QUANTITY
To calculate 30% of $58 you would multiply 58 by 30 divided
by 100. Because 30 and 100 are both divisible by 10, you would
multiply 58 by 3 and divide by 10.
58 ×^30 /^100 = 1,740/^100 = 17.4 or $17.40
If you are not sure how to do the calculation, simplify the numbers
to see how you do it. For instance, let’s say you want to fi nd 23%
of 485 and you don’t know what you have to multiply or divide; try
the same calculation with easy numbers. How do you fi nd 50% (½ )
of 10? You can see that you multiply 10 by ½ or you multiply by
⁄. Th en you can apply this method to fi nding 23% of 485. You
substitute 23 for 50 and 485 for 10.
You would get:
485 ×^23 / 100 = 111.55
You can check by estimation by saying that 23% is almost a quarter,
and a quarter of 400 is 100.
Percentages are used in all areas of life: percentage discounts,
percentage profi ts, statistics, sports results and examination scores.
We meet them every day.
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