Counting Significant Figures (Sig Figs)
Name: ________________________
Date:_____________
pearsongreatpath.wikispaces.com
RULE -1: If the decimal is Present: Find the first non zero on the left, then count all digits to the RIGHT
If the decimal is Absent: Find the first non zero on the right, then count all digits to the LEFT
RULE-2: Every digit in scientific notation is Significant
RULE-3: Any number that is counted is an EXACT number and has UNLIMITED significant digits.
Practice Problems: Identify the number of significant digits in each of the following
1) 23.7 x 10-2 cm 2) 1.4 x 107 L
3) 4.293 x 104 km 4) 705 seconds
5) 600 cm
6) 4301.0 GHz
8) 40280 daL
10) 8 students
Answers 1) 3
7) 0.00056 dg
2) 2
3) 4
4) 3 (it is possible to 705.2 seconds)
9) 24 Megapixels
5) 1
6) 5
7) 2
8) 4
9) 2
10) Unlimited
MORE Practice Problem: Identify the number of significant digits in each of the following
1) 192 rulers
2) 5,400 km
3) 100.0 minutes 4) 7.29 years
5) 0.000004 m
6) 8,000,000 m/s
7) 0.010060 hL
8) 10.02 cg
10) 357 dam
Answers 1) Unlimited
2) 2
3) 4
4) 3
5) 1
6) 1
9) 52 teeth
7) 5
8) 4
9) Unlimited
10) 3
EVEN MORE Practice Problem: Identify the number of significant digits in each of the following
1) 409 cars
2) 51.050 L
3) 0.000007
4) 6.52 x 10-5 kg 5) 5,000 staples
6) 738.000 Mm
7) 7.20 x 108 kL
8) 31 light years
9) 30 m
Answers: 1) Unlimited
2) 5
3) 1
4) 3
5) unlimited
6) 6
7) 3
8) 2
9) 5
10) 16
10) Can not determine – no units listed
NOTE: Use the following information to answer questions # 21 and # 22 on the back side of this page:
Determining Accuracy: Compare the accepted (true) value to the AVERAGE of the experimental trials
Determining Precision: Subtract the lowest measurement from the highest measurement
HOME WORK - How many significant figures are in each of the following numbers?
NOTE: Be careful of the units, some of them are TRICKY 
11)
1.2 x 103 mice ____
210 seconds ____
12)
0.00120 minutes ____
3)
801.5 kg ____
13)
30.0 L ____
4)
4,000 mm ____
14)
9.010 x 10-6 kg ____
5)
101.0100 kL ____
15)
2,370.0 light years ____
6)
11 dogs ____
16)
6.200 x 10-4 km ____
7)
27 dag ____
17)
18 GHz
8)
1500 rulers ____
18)
27
9)
.0007 km ____
19)
3 x 100 m ____
10)
0.0300 mL ____
20)
200. L ____
1)
5.40 m
2)
____
____
____
Students were asked to determine the concentration (M) of acetic acid in a brand of barbeque sauce.
The results of three of the students are in the table below:
Andy
0.102 M
0.104 M
0.100 M
Trial -1
Trial -2
Trial -3
Brenda
0.097 M
0.094 M
0.10 M
Curt
0.0960 M
0.109 M
0.118 M
Average
21) If the accepted (true) concentration of acetic acid is 0.096 M, which student was the most precise?
Explain your answer.
22) If the accepted (true) concentration of acetic acid is 0.096 M, which student was the most accurate?
Explain your answer.
23) What is wrong with Brenda’s third measurement of 0.10 M?
24) What is wrong with Curt’s first measurement of 0.0960 M?
25) Calculate the error and percent error for Andy if the accepted (true) concentration is 0.096 M