Mathematics for IGCSE & O level - Estimation (Section 3 - No. 31)
What are the key points to remember about significant figures?
Zeros within a series of digits are counted as significant.
When rounding to a given number of significant figures, you count from the first non-zero digit.
When rounding to a given number of decimal places, you count the number of places from the decimal point.
To find an estimate to the answer to a problem, round each of the numbers to one significant figure and then perform the calculation.
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All of the listed items are key points to remember about significant figures.