Find a number

*A*such that*A*% of 75 = 75% of*A*.The answer is that A can be absolutely any number you like!

A general rule is that

*A*% of*B*=*B*% of*A*.Easy to see why.

*A*% of*B*= (*A ×**B*)/100 and*B*% of*A*= (B*×**A*)/100.Sometimes this is a useful little result. For example, to find 40% of £75, change it to 75% of £40, which is easy, (because 75% is just three-quarters). So the result is £30.

Similarly, what's 17% of £50? Well it's the same as 50% of £17, which is half of £17 = £8.50.

Back to the book.

## No comments:

## Post a Comment