Mathematics for IGCSE & O level - Estimation (Section 3 - No. 5)
What is a common mistake when rounding to a given number of significant figures?
Using the wrong operation.
Ignoring the non-zero digits.
Counting the wrong number of zeros.
Rounding up when you should round down.
Explication
A common mistake is to include the wrong number of zeros, or to exclude zeros that should be included.