## Chemistry: Molecular Approach (4th Edition)

Published by Pearson

# Chapter 1 - Exercises - Page 39: 82

#### Answer

Each of the given number is rounded to three significant figures are: a) 79,800 b) 1.55 c) 2.35 d) 0.0000454

#### Work Step by Step

The significant figures of a number are digits that make the measurement more precise. This includes all digits except 1. All leading zeros. 2. Trailing zeros when they only indicate the scale of the number. 3. All extra digits that are introduced to make the calculations carried out more precise than the original data. Rounding off follows these rules: 1. If the last digit is less than 5, then the number is rounded down; that is, number is written till the previous digit. 2. If the last digit is 5 or more, then the number is rounded up; that is, 1 is added to the previous digit and our digit is dropped. a) 79,800 because 8 is succeeded by 4, so it is rounded down that is, number is written till the previous digit. The zeros in the end of whole numbers are insignificant. b) 1.55 because 4 is succeeded by 8, so 4 is rounded up to 5 and everything else is insignificant. c) 2.35 because 4 is succeeded by 9, so 4 is rounded up to 5 and everything else is insignificant. d) 0.0000454 because initial zeros are insignificant in decimal numbers and 3 is succeeded by 8, so 3 is rounded up to 4.

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