TECHNICAL MATHEMATICS
2d
Unit Conversion
show you work.............
remember units..................
Use Conversion Factors to change units:
1 in = 2.54 cm
equal quantities.
When dividing 2 equal quantities, the quotient is 1
EXAMPLES:
∴
1 in = 2.54 cm
2.54 cm
1
1 in
or
1 in
1
2.54 cm
1 ft = 12 in
1: Change 8 in to cm.
8 in 
2.54 cm  8 in  2.54 cm 

 20.32 cm
1 in
1 in
2: Change 118 cm to feet
118 cm 
1 in
1 ft 118 11 ft


 3.87 ft
2.54 cm 12 in
2.54 12
2
2
2
3: Change 18 in to cm :
18.0 in2 
2.54 cm = 1 in
 2.54 cm  6.45 cm2

 
1 in 2
 1 in 
6.45 cm2
 116 cm2
2
1 in
dearthdancer@rrc.ca
Academic Success Centre
www.rrc.mb.ca/lac
http://www.youtube.com/rrcwiseguys
http://blogs.rrc.ca/delaney/
2012
Page | 1
TECHNICAL MATHEMATICS
Pick the conversion factor that works....
Metric – Imperial Relationships
Common Imperial Units
Length or Distance
1 m = 10-3 km (or 0.001 km) = 3.2808 ft = 39.37 in.
12 inches (in) = 1 foot (ft)
3 feet (ft) = 1 yard (yd)
5280 feet (ft) = 1 mile (mi)
Weight or mass
1 m = 1.0936 yd
1 km = 0.6213 miles
1 ft = 30.5 cm = 0.3048 m = 12 in
16 ounces (oz) = 1 pound (lb)
1 in = 2.54 cm = 25.4 mm
1 m2 = 104 cm2 = 10.76 ft2
Capacity or Volume
1 m3 = 103 (or 1000) L = 35.3 ft3 = 264 US gal
2 pints (pt) = 1 quart (qt)
4 quarts (qt) o= 1 gallon (gal)
1 litre = 103 cm3 = 1.056 qt = 0.264 US gal
Time
4.54 L = 1 Imp. gal
1 day (d) = 24 hours (h)
1 hour (h) = 60 minutes (min)
1 minute (min) = 60 seconds (s)
1 h = 60 min = 3600 s
1 hp = 745.7 W
The symbol ” means inches (7” = 7 in) OR
seconds (45” = 45 seconds).
1 rad = 57.3°
The symbol ’ means feet (4’ = 4 ft) OR
minutes (34’ = 34 minutes).
Note: Imperial Gallon and US gallon are different
Ask yourself: Does the answer make sense??
Use conversion factors to change the units as indicated: (Use appropriate units in answer.)
Round answers to nearest hundredth (if applicable).
1. Change 42 cm to inches.
2. Change 27 Imp. gal. to litres.
3. Change 12 km to metres.
4. Change 9.375 in to centimetres.
dearthdancer@rrc.ca
Academic Success Centre
www.rrc.mb.ca/lac
http://www.youtube.com/rrcwiseguys
http://blogs.rrc.ca/delaney/
2012
Page | 2
TECHNICAL MATHEMATICS
5. Change 0.78 h to seconds.
6. Change 12 ft. to centimetres.
7. Change 54 cm to feet.
8. Change 657 109 mg to kilograms.
9. Change 63 km/h to metres per second.
10. Change 4.8 ft to metres.
11. Change 15 Imp. Gal to millilitres.
12. Change 315 cm/s to metres per hour.
13. Change 31 in2 to cm2
14. Change 562 980 mm2 to square metres.
15. Change 32.7 ft3 to cubic metres
ANSWERS:
1. 16.54 in.
5. 2 808 s
9. 17.5 m/s
13. 200.00 cm2
2. 122.58 L
6. 365.76 cm
10. 1.46 m
14. 0.56 m2
3. 12 000 m
7. 1.77 ft.
11. 68 100 mL
15. 0.93 m3
4. 23.81 cm
8. 0.66 kg
12. 11 340 m/h
dearthdancer@rrc.ca
Academic Success Centre
www.rrc.mb.ca/lac
http://www.youtube.com/rrcwiseguys
http://blogs.rrc.ca/delaney/
2012
Page | 3