Significant Figures

“SIG FIGS”

What are Significant Figures?

• In science we say that significant figures are the figures (#’s) in a measurement that consist of all of the numbers known plus one # which is somewhat uncertain or estimated.

What measurement is represented in the diagram?

• 2.35 cm

• How many “sig figs”?

• 3

Rules for Sig Figs

• All non zero numbers are Significant.– Ex. 45.87

• 4 significant figures

Numbers with zeros

Zeros appearing between non-zero numbers are significant.– Ex: 7089 4 sig figsZeros to the LEFT of a number are NOT

SIGNIFICANT. (they are just placeholders)Ex. 0.000378 3 sig figs Zeros at the end of a number and to the right

of a decimal point are significant.Ex. 7.500 4 sig figs

Zero rules cont.

• Zeros at the end of a measurement are questionable.

• Ex: 100. 3 sig figs

• Ex: 100 ? Ask the source

• If there is no decimal at the end assume that the zeros are NOT significant

Try a few examples