Question: What is Significant Figures ?


The most significant figure in a number is the first non-zero digit starting from the left. In the number 238.95, for example, although the left-hand digit is only 2 it represents 200, while the largest digit 9 only represents 9 tenths. The next most significant digit is the 3 for it represents 30, while the least significant digit is the 5 as it only represents 5 hundredth. Numerical calculations are often rounded off to a specified number of significant figures, shortened to sig. Fig. Or s.f. The examples below show the result of various calculations, and the effect of rounding them to the number of significant figures stated:

9.434 285 to 4 Significant Figures is 9.434
546.3287 to 3 Significant Figures is 546
0.490 12 to 3 Significant Figures is 0.490
0.002 054 to 2 Significant Figures is 0.0021.