Chapter 1:Unit 11. Significant figures used in Calculations

Significant Figures in Calculations

Operational Rules:

1. In multiplication and division, the number of significant figures in the final answer is the same as the lowest number of significant figures in the measurement.
2. In addition, or subtraction, the number of significant figures in the final answer has the same number of decimal places as the digit with lowest decimal places used in the measurement.
   https://www.youtube.com/watch?v=iorZdz4dsBU&t=2s

Example:

A) Determine: 25.3+ 12.84+ 486
486
25.3
12.84
524.14

Final ans: 524( lowest zero decimal place used in calc)

B) Determine: 15.6 × 13.523 * 0.0081

The original answer is 1.70876628

Lowest sig fig used in calc. is 2 (0.0081). Therefore, the final answer is 1.7

Sometimes exponents are used in calculations. Note that, powers are added while number are multiplied, and subtracted when numbers are divided.

For example:( (1.35 × 10⁷ ) × ( 6.2 × 10^-3 )=  8.37 × 10⁴

Final answer: 8.4 × 10⁴

Questions:

1. Perform the following computation and express your answer with proper significant figures.
   a)7321 × 0.0021
   b) 340/0.0031
   c) 3+ 1.2 + 1.8
   d) 73 × (17.6-13.73)

Ans: a) 15
b) 110000
c) 6
d) 280