9/12/2009

3. A B
1 2.7 4
2 2.8 4
3 3.1 4
4 2.9 4
5 3.3 4
6 2.8 4

4.  Why do we use significant digits?
• Because any measurement involves errors

6.  What is the difference between 26kg and
26.0kg? Accuracy!
 Finding significant digits
 Rule 1:
• Look for a decimal point.
• e.g. 26kg. NO decimal point
• e.g. 26.0kg.YES decimal point
• e.g. 26.0000kg.YES

7.  Rule 1: Look for decimal point
 Rule2: if there is no decimal point, the
zeros at the end do not count.
• 26kg
• 260kg
• 2600000000kg
• (all have 2 significant digits)

8.  Rule 1: Look for decimal point
 Rule2: if there is no decimal point, the
zeros at the end do not count.
 Rule3: if there is a decimal point, the
zeros at the beginning do not count.
• 0.003kg (1 significant digit)
• 0.0030kg (2 significant digits)
• 0.0030000kg (5 significant digits)
• 1.0030kg (5 significant digits)

9.  .0026701 kg
 2.6701 kg
 2.67010 kg
 2.670100 kg
 10.0550 kg
 3500 m
 1,809,000 L

10.  3.052 m X 2.10 m X 0.75 m =
 4.8069 m3
 Which number has the least number of
significant digits?
 The answer has the same # of significant
digits as the number with the smallest #.
 4, 3, 2. Answer = 4.8069 m3
.
 4.8 m3

11.  100
=1
 101
=10
 102
=100
 10-1
=0.1
 10-2
=0.01
 17 = 1.7 x 101

12.  32,700
• 3.27 x 104
 1,024,000
• 1.024 x 106
 .0047100
• 4.71 x 10-3

13.  A. Find the number of significant digits
in:
• a) 400 b) 4000 c) 400.1 d) 400.10
• e) 0.001 f) 0.0010
 B. Scientifically notate:
• a) 0.0358
• b) 358,000