Tuesday, September 8th

• Grab your calculator• Prepare for warm up #4• Test on Thursday

Warm up #4: I want a car!

• You are trying to save up for a car. The car costs $7500.00. You have been getting about $350/wk for about 12 weeks. You also got a $500.00 check from your grandparents for your birthday that you are going to use toward your car. You parents gave will give you $1000 towards the purchase of your car.

• How much money do you have so far?

350 X 12 = $4200 + 500.00 + 1000 $ 5700OR$ 5700.00?

DISCUSS

YOU ARE ONLY AS PRECISE AS YOUR LEAST PRECISE MEASUREMENT!

The bones

• These dinosaur bones are 85,000,004 years old

• Wow! That is VERY precise. How do you know exactly how old they are? I mean, down to the year?

• That’s easy! They were 85,000,000 years old when I started working here, and I have worked here for 4 years, so now they are 85,000,004 year old!

465,000• For large numbers, zeroes after the last non-zero number

before the decimal are giving information about the size of the number.

• The zeroes act as place holders that are still showing you the size of the number.

• 465,000 is NOT the same as 465, but both have the same number of significant figures

• If someone has a bank account and they say they have $465 in it, you think they are being very precise

• If someone has a bank account and they say they have $465,000 in it, you probably think that this is more of an estimate than an exact number

• More likely they would round that number up and say they have $500,000 or half a million

How many sig figs?

• 45,000• 450• 45• 300,000,000• 30,000,000• 3,000

• 2• 2• 2• 1• 1• 1

450.00

• How many sig figs?• 5• Think about it as if it were money: your mom

asks you how much money you have in your bank account to last until next payday.

• If you answer, “450 dollars,” your mom will think that you have ABOUT 450

• If you say, “ I have 450 dollars and zero cents,” it is more specific

How many sig figs?

• 56• 56.0• 56.00• 56.01• 56.10• 560.00• 5600.00• 5600• 560

• 2• 3• 4• 4• 4• 5• 6• 2• 2

0.000465

• Zeroes between the decimal and the 4 are telling how SMALL the number is

• 0.000465 is NOT the same number as 0.465, but they have the same number of sig figs

• The zeroes act as place holders

How many sig figs?

0.0050.05.050.03680.03600.0300.03000.00400560.00400500.0040000

1113333555

Ex: 35.00 X 4.5 / 823.465Which of the three numbers has the FEWEST sig figs?

4 2 6

4.5 has the fewest number of sig figs (2)ROUND your answer to 2 sig figsWhat your calculator tells you: 0.191264959

Correct ans: 0.19

What is the correct answer?

• 45.6 X 2.3

• 0.156 X 22• 6.7 / 23.461

• 105• Your calculator gives

you 104.88 but you must round to 105

• 3.4• Calculator gives you

0.285580324• Can only have 2 sig figs• Correct answer: 0.29

What is the correct answer?

• 6.7 x 9.45• 22.0 X 43.1• 3.14 X 65.90• 0.0560 X 22.45• 48.0 / 67.89• 0.0300 X 8.156

• 63• 948• 207• 1.26• 0.707• 0.245

Ex: 13.67 + 5.3785 - 2.9

Which of the three numbers has the smallest amount of numbers past the decimal?

EX: 13.67 + 5.3785 – 2.9

24

1What your calculator gives you: 16.1485

16.1

What is the correct answer?

• 14.678 +32.5

• 44.64 -50• 88.56 -42.673• 3.75 + 4.1• 21.342 -4.6• 31.2 + 4.56 -5.157

• 47.2• Calculator gives you

47.178 but you must round to 1 place past the decimal

• 5• 45.89• 7.6• 16.7• 30.6

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