B. Significant Figures

1. Definition

In each of our taping examples, we stated the measurement to the smallest marked division on the tape and then interpolated the next digit. For example, we reported 9.83 ft with a tape divided to tenths, Figure B-1:

 Figure B-1
Measurement Interpolation


When we report a measurement, we’re conveying its magnitude (size) and resolution (which can imply accuracy). We do this using significant figures (sig fig). The number of sig fig in a number is all the digits of which we’re certain plus an additional estimated digit. Our 9.83 ft distance has three sig fig.