Question

How to round off 2.252 to 2 significant figures?

Answer 1

Significant Figures

• ​The significant figures of a given number are those significant or important digits, which convey the meaning according to its accuracy.

Rules for Significant Figures

• All non-zero digits are significant. for example, 198745 contains six significant digits​
• All zeros that occur between any two non-zero digits are significant for example, 108.0097 contains seven significant digits​
• All zeros that are on the right of a decimal point and also the left of a non-zero digit is never significant. for example, 0.00798 contains three significant digits​
• All zeros that are on the right of a decimal point are significant, only if, a non-zero digit does not follow them. for example, 20.00 contains four significant digits​.
• All the zeros that are on the right of the last non-zero digit, after the decimal point are significant. for example, 0.0078900 contains five significant digits​.
• All the zeros that are on the right of the last non-zero digit are significant if they come from a measurement. for example, 1090 contains four significant digits​.

Rounding off a number

• If the number you are rounding off is followed by 5, 6, 7, 8, or 9, round the number up. for example, 3.56​ can be rounded to nearest ten is 3.6
• If the number you are rounding off is followed by 0, 1, 2, 3, or 4, round the number down. for example, 3.54​ can be rounded to nearest ten is 3.5

Hence, the number 2.252 rounded off to two significant figures becomes 2.3.