Math vs. Science

• to a mathematicianmathematician:

73 = 73.0 = 73.00 = 73.000 etc

• to a scientistscientist, these numbers have a more complicated meaning

Numbers in ScienceNumbers in Science

countscounts are exact and have infinite number of significant figures

• there are 30 desks in this room

30 = 30. = 30.0 = 30.00 = 30.000 desks

significant figures are used for data calculations in chemistry because..•dealing with large numbers of very small particles

–often written to power of 10 • ex: (3.26 x 10-5)

How do I figure out how many

Significant Figures?

X

X

the easiest way to count sig figs is by the easiest way to count sig figs is by using the using the Atlantic and Pacific RuleAtlantic and Pacific Rule

the easiest way to count sig figs is the easiest way to count sig figs is by using the by using the Atlantic and Pacific Atlantic and Pacific RuleRule

to help determine how to count # of to help determine how to count # of sig figs sig figs ask yourself this question:ask yourself this question:

does the number have a decimal pointdoes the number have a decimal point? ?

decimal point decimal point Absent Absent start counting fromstart counting from AtlanticAtlantic Ocean (right side) of # Ocean (right side) of #

decimal point decimal point Present Present start counting from start counting from PacificPacific Ocean (left side) of #Ocean (left side) of #

Decimal point absent:•Start on Atlantic (right) side of #

•Start counting with first non-zero non-zero digit & count until reach end of #

5400 m has 22 sig figs5431 m

has 44 sig figs

54005431

Decimal point present:

•Start counting with first non-zeronon-zero digit & count until reach end of #

2545.300 g

0.004530 km

has 77 sig figs

has 44 sig figs

•Start on Pacific (left) side of #

2545.300

0.004530

sometimes,after math calculations youranswer may not contain enoughsig figsbecause… there are zeros that are notconsidered significant

answer: 5300 but need 3 sig figs

if you want a zero to be significant draw a line above to show that it is significant

once in a BLUE MOON BLUE MOON rulerule

5300 cm becomes:

5300 cm_

when doing calculations that involve:

Multiplication Multiplication and Divisionand Division

answer: only have as many sig sig figsfigs as data number with least least numbernumber of sig figs

24.56 cm x 14 cm =

1. 343.84 cm2

2. 343.8 cm2

3. 343 cm2

4. 340 cm2

correct correct answer: answer: 44

2 sig figs

when doing calculations that involve:

Addition and SubtractionAddition and Subtraction

answer: only have as many decimal placesdecimal places as data number with least numberleast number of decimal places

422.63 cm 29.472 cm 115.9 cm________________+

a) 568.002 cm

b) 568.00 cm

c) 568.0 cm

d) 568 cm

correct correct answer: Canswer: C

1 decimal place