Rounding numbers

How to round numbers

Make the numbers that end in 1 through 4 into the next lower number that ends in 0. For example 74 rounded to the nearest ten would be 70.

Numbers that end in a digit of 5 or more should be rounded up to the next even ten. The number 88 rounded to the nearest ten would be 90

You can round off a number in different ways: Example:
to the nearest unit: 643,78 = 644,
to the nearest 10 (ten) --> 643,78 = 640
to the nearest 100 (hundred) --> 643,78 = 600
to the nearest 1/10 (tenth) --> 643,78 = 643,8

More interactive exercises:
http://www.bbc.co.uk/education/mathsfile/shockwave/games/roundoff.html
http://www.aaamath.com/est27a-rounding.html