### 1stPhyHWSolutions

```HOW MANY SIG FIGS ?
200
1 sig fig
Zeros are place
holders
3.002
4 sig fig
Zeros are between
sig figs
.00034
2 sig fig
Zeros are place
holders
.7000
4 sig fig
Zeros are exact
zeros
HOW MANY SIG FIGS ?
3005
4 sig fig
Zeros are between
sig figs
5.600
4 sig fig
Zeros are exact
zeros
3000.0
5 sig fig
1000
3 sig fig
Last zero is exact
and others are in
between
Bar makes place
holders significant
Rounding to Sig Figs
1 sig fig
3 sig fig
5 sig fig
7 sig fig
Need the bar to
make the place
holder significant
1.55 x 106 nm =
km
This is just a metric conversion ---- always 2 steps.
you’re given:
One step to the
BASE unit, meters:
One step to the desired
unit, kilometers:
1.55 x 106 nm x 1x10-9m x
1 nm
3 sig figs
1 km
1x103 m
1.55x10-6 km
.00000093 Tg =
g
This is just a metric conversion ---- always 2 steps.
you’re given:
One step to the
BASE unit, grams:
12
1x10
g
.00000093Tg x
1 Tg
2 sig figs
One step to the desired
unit, micrograms:
x
1 g
1x10-6g
9.3x1011 g
8.5 x 10-20 Ml =
ml
This is just a metric conversion ---- always 2 steps.
you’re given:
One step to the
BASE unit, liters:
8.5 x10-20 Ml x 1x106 l
1 Ml
One step to the desired
unit, milliliters:
x
2 sig figs
Or you could use this for last fraction 
1 ml
1x10-3 l
1000 ml
1 l
8.5x10-11 ml
8 gallons =
liters
Gallons is an English unit and liters is a metric unit - determine what
Metric-English conversion will work (from box at top of homework)
you’re given:
8 gal
x
4 qt
1 gal
x
.94 l
1 qt
1 sig figs
30.08 liters
30 liters
5.75 x 1015 s =
you’re given:
years
Keep converting to bigger units of time
until you get to years:
5.75 x1015s x 1 min x 1 hr x 1days x 1 yr
60 s
60min 24 hr 365days
3 sig figs
1.82x108 yr
500 ml/min =
qt/hr
This has 2 dimensions. Convert ml to qt and min to hr
you’re given:
ml is on top
Min on bottom
1 qt
500 ml
1x10-3 l
x
x
min
.94 l
1 ml
1 sig figs
60 min
x
1 hr
31.9 qt/hr
30 qt/hr
9 in2 =
Need 2 factors of inches to cancel
inches squared
you’re given:
9 in2
1 sig figs
cm2
x
2.54 cm
x
1
in
2.54 cm
1 in
58.06 cm2
60 cm2
```