Estimation and Rounding

Math is an 'opportunity gateway.

Estimating

It is an important part of mathematics and a very handy tool for everyday life.

Rounding off is a kind of estimating.

Find the place value you want (the "rounding digit") and look at the digit just to the right of it.

In math, you can round up or round down.

Rounding up happens when you have a value that is half or greater of the amount you are rounding. Let's say you want to round to the nearest ten. If you were given the value 26, you would round up because 6 is greater than half of ten (5). If you were given 25, you would also round up. Rounding down happens when the value is less than half. Using the same examples, if you were given the number 24 you would round down because the four is less than five. Even if you were given the wacky decimal 24.9999, you would still round down because 4.9999 is less than five.

Here are some more examples:

Round 34 to the nearest 10 -- 30
Round 678 to the nearest 10 -- 680

It works for hundreds and thousands too.

Round 494 to the nearest 100 -- 500
Round 627 to the nearest 100 -- 600
Round 5,872 to the nearest 1,000 -- 6,000
Round 8,452 to the nearest 1,000 -- 8,000

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Significant Figures 

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