Significant Figures and Rounding

Counting Sig. Figs. Pacific a.k.a.: Present Start with first non-zero, go in  direction Atlantic a.k.a.: Absent Start with first non-zero, go in  direction Steps to Count # of Sig. Figs. 1.See if decimal is present or not. 2.Go from correct direction. 3.Start counting at 1 st Non-Zero # 4.Keep counting until you run out of #s

Examples 1.300,150 a.Decimal point absent – 5 sig figs a.Decimal point present – 4 sig figs a.Decimal point absent – 1 sig fig a.Decimal point present – 2 sig figs a.Decimal point present – 5 sig figs

Rounding Sig. Figs. 1.Always start from the LEFT 2.Start counting at the 1 st non-zero # 3.Count to the correct # of Sig. Figs. 4.Round that # a.If that # is a 0 before the ones position, then turn to sci. not. and then round. 5.For every # after the rounded position a.If before decimal, turn to zero b.If after decimal, drop

Example – Round to 2 S.F. 1.Always start from the LEFT Start counting at the 1 st non-zero # Count to the correct # of Sig. Figs Round that # Final Answer: 0.066

Example – Round to 3 S.F. 1.Always start from the LEFT Start counting at the 1 st non-zero # Count to the correct # of Sig. Figs Round that # Final Answer:

Examples: a) (4 S.F.) b) (2 S.F.) c)1.506 x 10 4 (3 S.F.) d) (3 S.F.) e)100 (2 S.F.)

Determining the Number of Sig Figs in Calculations