EVERYDAY SCIENCE

Detailed explanation-1: -We round a number to three significant figures in the same way that we would round to three decimal places. We count from the first non-zero digit for three digits. We then round the last digit. We fill in any remaining places to the right of the decimal point with zeros.

Detailed explanation-2: -The number 3.845 rounded off to three significant figures becomes 3.84 since the preceding digit is even.

Detailed explanation-3: -The quantities 0.456, 0.0456 and 0.00456 all contain 3 significant figures. In this case, you need to think in terms of exponential numbers. 0.0456 is 4.56 x 10-2 (only 3 significant figures) and 0.00456 is 4.56 x 10-3 (again, only three significant numbers).

Detailed explanation-4: -Since it is also a 9, it rounds up to 10, which carries over to the 2 second digit, and then to the first. This means that 0.9999 rounded to three decimal places is 1.000.