1. Units and Significant Digits

2. Standards of Length, Mass and Time
MKS System (SI units)
Length – Meter ( 1/299,792,458 distance light travels in a vacuum in one second
Mass – Kilogram (Mass of the International Prototype Kilogram, a/k/a “Le Grande K”)
Time – Second (9,192,631,770 periods of the radiation from cesium-133)

3. Prefixes for SI 10-24 yocto 10-21 zepto 10-18 atto 10-15 femto 10-12
pico
10-9
nano
10-6
micro
10-3
milli
10-2
centi
10-1
deci
1024
yotta
1021
zetta
1018
exa
1015
peta
1012
tera
109
giga
106
mega
103
kilo
102
hecto
101
deka

4. Significant Digits Significant Figures (Sig Figs)
Four Significant Digits
Two Significant Digits
1, ? Significant Digits
1.50 x 103 Three Significant Digits

5. Only significant to the limit of any single term
Adding/Subtracting
= 579
x 106 =
4.56 x 106
Only significant to the limit of any single term

6. Multiplying/Dividing
123.4 x 456 = 5.63 x 104
Only significant to the smallest number of significant digits in any single term