We learned how to convert measurements between Imperial and SI units.

Converting between,
SI (metric) to SI, Imperial to Imperial, SI to Imperial and vice versa.
SI is the measurement system that is used in Canada and most country.
Imperial measurement system is used in United States, Liberia and Myanmar (Burma).

SI measurement system uses (mm, cm, m, etc)
Imperial measurement system uses (in, ft, yd, etc)

Some examples

Converting within imperial

12 ft 3 in to inches
12ft x
12 x = 144 in
144 + 3 = 147 in
12 ft 3 in = 147in
There are 12 inches in 1 foot. You put whatever unit you want to get rid of in the denominator.

Converting within SI

35mm to metres
35mm x 
35 x  = 
= 0.035 m
35 mm = 0.035m

Converting SI and Imperial

8ft 3in to metres
feet to inches to centimetres to metres
8ft x  = 96in
96in + 3in = 99in
99 x  = 251.46cm
251.46cm x  = 
= 2.5146m
8ft 3in = 2.5146m