Significant Figures

Rules: #1 – Nonzero digits are significant

1931178621,237,983

#2 – Zeros between significant figures are significant109500265071,000,341

Rules#3 – Final zeros after a decimal are

significant10.0234.002986.00010000.00

#4 – Zeros that are placeholders are NOT significant100.0003350,0000.099

RoundingWhen rounding to a specific amount of significant figures:

In scientific notation, all numbers preceding “x10” are

significant

5-9 as next digit: round up

1-4 as next digit: round down

If you end up with zeros that need to be significant, but are

not:

Add a decimal at the end of the number

All previous digits are then significant

100 rounded to 3 significant digits = 100.

Add a bar over the final significant zero

100 rounded to 2 significant digits = 100

The Quick Method:If there is a decimal, count all digits to the

right of the first nonzero digit as significant.0.001500.000510.01010,120.0

If there is NOT a decimal, count all digits to the left of the first nonzero digit.10,000230,4502501,205,375,000