Question

how do you convert 2.5lb to oz

Answer 1

1lb = 16 oz

Times the numbers of lbs you have by 16 to get total oz

Answer 2

There are 16 ounces in a pound. 2.5 pounds = 40 ounces

Answer 3

You do this:

http://lmgtfy.com/?q=2.5lb+to+oz

Answer 4

use the conversion factor that @jarobins gave you and put it into a fraction (the fraction equals one and you can always multiply by one)
\[(2.5lbs)*(\frac{16oz}{1lb})\]
perform the number crunching and cancel out the units