Answer:
Take whatever you weigh in pounds and divide by 2.205.
Step-by-step explanation:
Because weight is a measure of the force you exert on the earth, with some simple manipulation of Newton's second law we can get your mass in kilograms. 2.205 is just a nice constant that does that for you, but the more in-depth version is that
F = ma
The equation for weight is thus
W = mg, where W is your weight in pounds, m is your mass, and g is the acceleration due to gravity (9.80 m/s^2)
Thus, your mass in kilograms is m = W / g.