In GMAT unit conversions are more important and we need to do it correctly and swiftly here is a tip for converting Kilos to Pounds.
20 kilos into pounds:
Step one: multiply the kilos by TWO.
21 x 2 = 42
Step two: divide the answer by ten.
Just put a decimal point one place in from the right.
42 / 10 = 4.2
Step three: add two step answers.
42 + 4.2 = 46.2
And thats the answer
21 kilos = 46.2 pounds