Question

An ant weighs about 2 x 10^-5 lb. There are about10^15 ants on earth. How many pounds of an ants are on earth?

Answer 1

to get the total weight, we multiply them:
2x10^(-5) * 1x10^15
to do this, first we multiply the first terms or the terms with no raised exponent,, thus that would be the 2 and 1:
2 * 1 = 2
next we multiply the second terms or the 10 raised to exponent,, to do this, recall that if the terms that we will multiply have the same base (here the base is 10) we can simply add the exponents:
10^(-5) * 10^15 = 10^(-5+15) = 10^10

finally we multiply the answers we got:
2 x 10^10 pounds

hope this helps~ :)