Basic Training 4th Annual ICP Conference

Significant Figures

• Numbers that contribute to resolution/precision of measurement Which numbers are significant?

• All non-zero numbers are significant

• Zeros are special

• Between 2 significant figures? – Significant • Leading zero? – Not significant • 0.0050 (2 significant figures) • Final zero? – Maybe (significant if part of the decimal portion)

• Scientific notation • 140 – 1.4 x 10 2 • 14.0 – 1.40 x 10 1

• 140 – No (2 significant figures) • 14.0 – Yes (3 significant figures)

More Significant Figures • Rules • Addition and Subtraction • If the number of decimal places are the same for all numbers, the final answer has the same number of decimal places as each individual number !"!. $% + '(. )* + ''. +" = $'+. )( (report to 2 decimal places) • If the number of decimal places are not the same for all numbers, the final answer has the same number of decimal places as the number with the fewest decimal places. $(. $-* + %. ) = %". (-* → %". + (report to 1 decimal place) • When adding/subtracting numbers in scientific notation, express all numbers with the same exponent. !. -%$ / !" ) + *. !"( / !" % + ". '+* / !" - = !. -%$ / !" ) + ". "*!"( / !" ) + '. +* / !" ) = !!. )!%"( / !" ) → !!. )! / !" ) (2 dp)