Significant figures = important numbers

Significant figures include all known digits plus one estimated digit

0.01 vs. 0.010 vs. 0.0100Which number is more precise?Deal with measured or computed values (as

opposed to values like 2 eyes, 12 eggs)

To what place can we record measurements on this graduated cylinder?

RULE 1: All nonzero digits are significant: 72.3 g has three

RULE 2: Zeroes between nonzero digits are significant. 60.5 g has three

RULE 3: Placeholder zeroes are NOT significant; such zeroes merely indicate the position of the decimal point.

0.0253 g and 4320 g have three RULE 4: All final zeroes to the RIGHT of a decimal point

in a number ARE significant. 6.20 has three

1. 508.0 L2. 0.049450 m3. 0.0084 mg4. 298.206 g5. 820,400.0 L

Calculators perform flawless arithmetic, however they are not aware of the number of significant figures that should be reported in the answer.

You need to apply the rules of significant figures and rounding to report a value correctly!

In addition and subtraction, the result is rounded off so that it has the same number of decimal places as the measurement having the fewest decimal places.

Adding/subtracting – line up the numbers, add ‘em up, and cut off at the shortest tail (round if necessary)

1.    37.76 + 3.907 + 226.4 = 

2.    319.15 - 32.614 = 

3.    104.630 + 27.08362 + 0.61 = 

4.    125 - 0.23 + 4.109 = 

1.    37.76 + 3.907 + 226.4 = 268.1

 2.    319.15 - 32.614 = 286.54

 3.    104.630 + 27.08362 + 0.61 = 132.32

 4.    125 - 0.23 + 4.109 = 129

Count number of sig figs in each of your numbers – the lowest number of sig figs is the number of sig figs that will be in your answer

32.7 x 2.519.9 x 100 135.5 5.7281 9.341

3.461728 + 14.91 + 0.980001 + 5.263123.1 + 4.77 + 125.39 + 3.58122.101 - 0.93070.04216 - 0.00041342.3 x 3.45 x 7.42 = 1.0007 x 0.009 = 51 / 7 = 208 / 9.0 =

(6.8 x 103) x (4.54 x 106)

(2.0 x 10 -1) x (8.5 x 105)

(4.42 x 10-3) x (4 x 10-2)

(1.92 x 10-2) (2.3 x 106)

(9.4 x 10 2) (1.24 x 10-5)

(9.2 x 10-3) (6.3 x 106)

Take out scientific notation worksheet from yesterday and try problems 9 – 14

Try it both ways: multiplying and dividing numbers and adding or

subtracting exponents Check your answer by using the EE button

Powers of 10 must be the same to add them together

If exponent becomes Larger, move decimal to the Left

(3.15 x 103) + (9.27 x 105)

(2 x 104 ) - (7 x 102)

** Convert so that you don’t get a negative number

(2.5 x 102 ) + (5.2 x 104 )

(4 x 103) + (3 x 102)

(9 x 102) + (1 x 104)

(2 x 102) - (4 x 101)

(3 x 10-6) - (5 x 10-7)

(9 x 1012) - (8.1 x 109)

Chocolate chip cookies:1 sugar1 brown sugar1 ½ butter2 ½ all purpose flour½ salt1 baking soda2 semisweet chocolate chips

SI Units – Systeme Internationale d’UnitesA universal system of measurement that allows people all over to discuss and trade without confusion

kilogram = kilogram

Time Length MassTemperatureAmount of a

substance

Second (s)Meter (m)Kilogram (kg)Kelvin (K)mole (mol)

The standard kilogram kept in a vacuum sealed container in France.

An SI unit that is defined by a combination of base units

What do density and volume units combine?

If you know the units, you can figure out the formula, or vice versa

What is the unit for speed?

Celsius or Kelvin

0 Co = 273 K Guess how you100 Co = 373 K solve for Kelvin

Fahrenheit to Celsius is a little harderFo = Co + 325

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