# CHEM 107 Lecture Notes - Lecture 1: Exothermic Process, Weighted Arithmetic Mean, Decimal Mark

## Document Summary

The rightmost digit of any quantity is al- ways estimated. The recorded digits both certain and uncertain are called sig. figures. The greater the # of sig. figures in a quantity, the greater its certainty. Measuring device used determines the # of sig. digits possible. 2. zeros b/t 2 non-0 #s are always sig. (5. 04 has 3 sig. figures) 0s that end a # before or after a decimal point are sig. 0s to the left of a # are not sig. they only serve to place the dec. pt. (0. 00003 & 0. 2 have non- sig. 0s that end a # w/o a dec. pt. generally not considered to be sig. but can be ambiguous. For xation and /ision the answer contains the same # of sig. figures as there are in the mea- surement w/ the fewest sig. figures.