Significant Figures Notes on PAGE _____

7.21 cm Significant Figures All of the known digits + 1 estimated digit 7.21 cm

Rule #1 All non-zero numbers are significant (numbers 1-9) 3.89 = __significant figures 938.3 = ___ significant figures 3 4

Rule #2 Sandwich rule: all zero’s between non- zero are significant 202 = __ significant figures 3

Examples Rule #2 8 6 67000045 = __ significant figures

Rule #3 Leading zeros are NOT significant (zeros at the front of a 1-9 number) EVEN WITH A DECIMAL

Examples Rule #3 2 2 0.0098 = ___ significant figures

Rule #4 Trailing (after) zeros are only significant WITH A DECIMAL in the number 202.00 = __significant figures 5

Practice the zero rules : 4 1000. = ___ sig figs 45000 = ___ sig figs 450.000 = ___ sig figs 0.004500500 = ___ sig figs 2 6 7

Practice the zero rules: 6 10.0098 = __sig digs 9800 = __ sig digs 0.009800 = ___sig digs 2 4

Significant Figures Lets get a better understanding 

Rule #5 Numbers obtained through counting or are defined have unlimited significant figures 60 minutes = 1 hour 24 people

Rounding Sig Figs Look at the digit to the right of the one you need to round. If is is < 5 – leave it alone If it is  5 – round up 56.312 m = _____ (4 sig figs) 56.31 m

Rounding 0.001775 m = ___________ (2 sig figs) 0.0018 m

46.352 Round the number to 3 significant figures. 46.4 46.4

46.352 Round the number to one significant figure. 50 50

46.352 Round the number to two significant figures. 46 46

Multiplication and Division The answer should be rounded to the same number of significant figures as the least number of significant figures in the calculation

Examples 6.4 m2 60 cm2 0.003483 cm2 4.56m x 1.4m = 5cm x 11cm = 0.0001800in x 19.35in = 60 cm2 0.003483 cm2

Sig Fig Practice #1 1.0070 m  5 sig figs 17.10 kg  4 sig figs How many significant figures in each of the following? 1.0070 m  5 sig figs 17.10 kg  4 sig figs 100,890 L  5 sig figs 3.29 x 103 s  3 sig figs 0.0054 cm  2 sig figs 3,200,000  2 sig figs