Do we need to learn by heart the conversion between yard,inch,foot,mile,ounce,pound,cup pint

In Cliff Gmat, the Math Review section has some conversion between these units and I find that it's really hard to remmeber
Ex:
12 inches (in) =1 foot (ft)
3 feet =1 yard (yd)
36 inches =1 yard
1,760 yards =1 miles
5,280 feet =1 miles
It's just about length, there are other units about Weight....

Do we need to learn these by heart for Gmat?

Thanks!