Significant Figures Rules

What are Significant Figures?

•They are all the numbers in a measurement that are known with certainty plus the first digit that is uncertain.

Why use Significant Figures?

•Significant figures are needed in science, because the tools we use to measure are not infinitely accurate.

Significant Figure Rules

1. Non-zero digits and zeros between non-zero digits are always significant.

1, 2, 3, 4, 5, 6, 7, 8, 9 are non-zero numbers

– they are always significant.

0046.78 – the zero’s are NOT significant

460.708 – the zero’s are significant because they are between non-zero numbers.

How many significant figures in the following numbers?

•36,838•7,038•800,005•036.73

2. Leading zeros are not significant.

004670.45

0.00245

The zero’s are NOT significant due to the fact

that they are leading zero’s.

How many significant figures in the following numbers?

•46,064•0.004704•0074,736.04

3. Zeros to the right of all non-zero digits are only significant if

a decimal point is shown.

350007370

37000The above zeros are NOT significant

The below zero’s are significant.64.0

35000.7370.

How many significant figures in the following numbers?

•67.300•2,800•9,000•8090.

4. For values written in scientific notation,

the digits in the coefficient are

significant.

6.02 x 1023

All the number in the coefficient (6.02) are

significant.

How many significant figures in the following numbers?

•5.048 x108

•8.00 x 10-4

•4.70 x 102

How many SIGNIFICANT FIGURES are in the following

numbers?

Write you answer in the space provided.

2 minutes.

1.83.591

2. 5007

3.10.005

4. 20 080

5.1 000 000

6.0.0012

7.1.007

8.196.0

9.75000.

10.82000

11.1.52x10 22

12.2.00 x10-6

Multiplying/Dividing with Sig Figs

• When multiplying or dividing using significant figures, the product or quotient will contain the same number of significant figures as the number with the least significant figures.

What is 23.95 x 11.7?

23.95 x 11.7

280.215

Answer with correct Sig. Figs.

280.

Adding/Subtracting with Sig Figs• When adding or subtracting with

significant figures, the sum or difference has the same number of decimal places as the measurement with the least number of decimal places.

What is 23.96 + 11.7?

23.96 + 11.7

35.66

Answer with correct Sig. Figs.

35.7

Do the following problems with the correct number of SIGNIFICANT FIGURES.

Write you answer on the back of the notes.

1.

24 x 31.8

2.

8.40/4.2

3.

49.1 + 8.001

4.

81.350 - 7.35

5.

0.0056 x 3.227

6.

1007/33.6

7.

20300 – 2878.6

8.

(1.5x1021) x (2.07x1013)

Use the information from these note to complete the Significant

Figures Worksheet.

Be sure to ROUND properly!!

Be prepared for a QUIZ over Significant Figures and Density

tomorrow