Rounding is a process of approximating a number by using fewer significant digits.

If it was required to round 357 to the nearest ten, one might choose 350 or 360, but since 357 is closer to 360 than it is to 350 (360 - 357 = 3 and 357 - 350 = 7), 360 is the better approximation of 357, when 357 is rounded to the nearest ten.

If it was required to round 352 to the nearest ten, one might choose 350 or 360, but since 352 is closer to 350 than it is to 360 (352 - 350 = 2 and 360 - 352 = 8), 350 is the better approximation of 352, when 352 is rounded to the nearest ten.

The process usually used in rounding is to look at the first digit to the right of the required rounding position and

• if it is 0, 1, 2, 3 or 4; round down
• if it is 5, 6, 7, 8 or 9; round up