Scientific rounding is like any other rounding with one small exception. When you are using signifcance to drive your values, numbers in the middle tend to round up (5 or higher rule) so they tend to the high side. It's a tiny amount but enough to change things. So, a rule for scientific rounding kind of levels it off.
When the rounding value is a five (5) and only a five, you have to make a decision about the rounding based on the number before it. Ready?
If the number before the rounding five is even, leave it alone. If it is odd, round up. Here are some examples:
12.45 to 3 SD = 12.4 (value before the 5 is even, simply truncate or chop off. I love the word truncate. It's a math word that sounds just a little violent!)
12.34 to 3 SD = 12.4 (value before the 5 is odd, round up)
34005 to 4 SD = 24000. Now the problem with this one is that 24000 only has 2 SD. I need that second from the left zero to be significant. I can do it one of two ways. 1) Put a line over it. That shows that it is a measured to value 2) Use scientific notation: 2.400 x 10^4.
This rule only applies when the rounder is a five.
Done? Go to: Percent Error |

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