SI Base Units
SI Base Units
Length
Meter (m)
Time
Second (s)
Mass
Gram (g)
Current
Ampere (A or amp)
Temperature
Kelvin (K)
Luminous Intensity
Candela (Cd)
Amount of Substance
Mole (mol)
Prefixes to Memorize
.
femto
f
10-15
pico
p
10-12
nano
n
10-9
micro
µ
10-6
milli
m
10-3
centi
c
10-2
deci
d
10-1
BASE UNITS
BASE UNITS
BASE UNITS
deka
da (or dk)
101
hecto
h
102
kilo
k
103
mega
M
106
giga
G
109
tera
T
1012
Significant Digits
Significant Figures
You may be asked to round to 3 significant
figures ( or possibly 4 or 5)
But first you must know how to determine
whether a number is considered significant
Rule 1
1. All digits 1-9 are significant
 789
 3 sig figs
 12587
 5 sig figs
 1.234
 4 sig figs
Rule 2 ~ BETWEEN
Any zero between two significant digits is
automatically significant
1003
 4 sig figs
 10.03
 4 sig figs
 1,000,007
 7 sig figs
Rule 3 ~ FINAL ZERO
Any FINAL ZERO (after the decimal
point) is significant.
 12.30
 4 sig figs
 3.5768000
 8 sig figs
 4.0
 2 sig figs
Rule 4 ~ placeholder
 Any zero is insignificant if it is not between two
sig digits nor the final zero after a decimal point.
Theses zeros are called placeholders.
 400
 1 sig fig
 10000
 1 sig fig
 789,600
 4 sig figs
 0.00059
 2 sig figs
 0.000590
 3 sig figs
Examples
30040 grams
4 sig figs
The last zero is not significant
0.663 kg
3 sig figs
The zero only located the decimal point
and is not significant
20.05 L
4 sig figs
1500 mg
4 sig figs
There is line over the final zero, so all
digits are significant
0.0008 grams
1 sig fig
The zeros are only place holders. They
are not significant
The End
Let’s practice!