Significant Figures Multiplication and Division Modern Chemistry, p. 47-48.

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Presentation transcript:

Significant Figures Multiplication and Division Modern Chemistry, p

Combining Significant Values As in addition and subtraction, when significant measurements are combined the precision of each must be considered. However, in multiplication and division, the focus is on how many sig figs are in each measurement.

Multiplication and Division So, count the number of sig figs in each measurement. Your answer can only have as many as the value with the least number of sig figs (just like that chain with the weak link). In other words, go with the fewest sig figs!

Multiplication and Division 1)344.0 x = How many sig figs in 344.0? How many sig figs in ?

Multiplication and Division 1)344.0 x = How many sig figs in 344.0?4 How many sig figs in ?

Multiplication and Division 1)344.0 x = How many sig figs in 344.0?4 How many sig figs in ?5

Multiplication and Division 1)344.0 x = How many sig figs in 344.0?4 How many sig figs in ?5 Write the number of sig figs over each value.

Multiplication and Division 45 1)344.0 x = Do the math!

Multiplication and Division 45 1)344.0 x = We only want 4 sig figs in the answer. Count from the first sig fig back through the number and draw a line to trim it.

Multiplication and Division 45 1)344.0 x = We only want 4 sig figs in the answer. Count from the first sig fig back through the number and draw a line to trim it. The answer is just 7606.

Multiplication and Division 2) ÷ 54 = Count the sig figs in each, and write the value above the number.

Multiplication and Division 6 2 2) ÷ 54 = Count the sig figs in each, and write the value above the number. And calculate…

Multiplication and Division 6 2 2) ÷ 54 = Trim…

Multiplication and Division 6 2 2) ÷ 54 = Trim… the answer is just 16.

Multiplication and Division 3) x x 67.0 = Count sig figs, write above

Multiplication and Division ) x x 67.0 = Count sig figs, write above and calculate…

Multiplication and Division ) x x 67.0 = Count sig figs, write above and calculate, then trim…

Multiplication and Division ) x x 67.0 = Count sig figs, write above and calculate, then trim…

Multiplication and Division ) x x 67.0 =  123…

Multiplication and Division ) x x 67.0 =  123… 12300

Multiplication and Division 4) ÷ (1.0 x 10 3 ) ÷ =

Multiplication and Division ) ÷ (1.0 x 10 3 ) ÷ =

Multiplication and Division ) ÷ (1.0 x 10 3 ) ÷ =

Multiplication and Division ) ÷ (1.0 x 10 3 ) ÷ =

Multiplication and Division 5) ÷ ÷ =

Multiplication and Division ) ÷ ÷ =

Multiplication and Division ) ÷ ÷ =

Multiplication and Division ) ÷ ÷ =

Multiplication and Division 6) x x 111 =

Multiplication and Division ) x x 111 =

Multiplication and Division ) x x 111 = 219,646.76

Multiplication and Division ) x x 111 = 219, ,646.76

Multiplication and Division ) x x 111 = 219, , …

Multiplication and Division ) x x 111 = 219, , … 220,000 or2.20 x 10 5

Multiplication and Division 7) ÷ 348 ÷ 3.0 =

Multiplication and Division ) ÷ 348 ÷ 3.0 =

Multiplication and Division ) ÷ 348 ÷ 3.0 =

Multiplication and Division ) ÷ 348 ÷ 3.0 =

Multiplication and Division 8) x x (2 x 10 2 ) =

Multiplication and Division ) x x (2 x 10 2 ) =

Multiplication and Division ) x x (2 x 10 2 ) = 6,581,497,286

Multiplication and Division ) x x (2 x 10 2 ) = 6,581,497,286 7

Multiplication and Division ) x x (2 x 10 2 ) = 6,581,497,286 7, 000,000,000 or 7 x 10 9