# Rounding problem regarding significant figures.

Posted by Nathan Alterton on September 27, 2000 12:54 PM

Here is my rounding problem:

If the first digit discarded is less than 5, do not change the last digiat retained. For example, 3.46325, if rounded to 4 significant figures, would be 3.463, if rounded to three digits, 3.46.

If the first digit discarded is greater than 5, or if it is a 5 followed by at least one digit other than 0, increase the last digit retained by one unit. For example, 8.37652, if rounded to 4 digits, would be 8.377, if rounded to three digits, 8.38.

If the first digit discarded is exactly 5, followed only by zeros, round the last digit upward if it is odd, but make no adjustment if it is an even number. For example, 4.365, when rounded to three digits, becomes 4.36. However, the number 4.355 would also round to 4.36, if rounded to three digits.

Please help! This is a common engineering rounding practice, so someone must know how to make Excel do this type of rounding!

Thanks

Nathan Alterton

Nathan_Alterton@dot.ca.gov