SOLUTION: Explain how you could estimate 22% of 78 to check if your answer is reasonable

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Question 489115: Explain how you could estimate 22% of 78 to check if your answer is reasonable
Answer by chessace(471) About Me  (Show Source):
You can put this solution on YOUR website!
Since these are multiplied, you can reduce one slightly and increase the other slightly and get something close to the actual computation, but in nice round numbers, easy to compute in your head.
So decrease 22% to 1/5 and increase 78 to 80.
80/5 = 16 is good (quick!) approximation to 17.16.
You could also note that 22% is about half way between 1/5 and 1/4.
80/4 = 20 is going to be too high (both factors are), but does give the range:
16 <= 17.16 < 20