posted by leslie on .
how do i find 1/3 of 9
2/5 of 25
in math, the word of means times so you would multiply 1/3 x 9 & 2/5 x 25. To set these problems up, you would change the whole numbers (9 & 25) into fractions, so you would have 1/3 x 9/1 for the first one, and 2/5 x 25/1 for the second one. When you line them up on your paper, you can either multiply straight across the tops & the bottoms then reduce, or you can cross-cancel before you multiply. Have you done cross-canceling?
You actually don't need to do all of the work Jesse has said. I'll show you a shortcut. Take the denominator (bottom part of a fraction) and divide it by your whole number. Then multiply that by the numerator (top part of a fraction). You can do it really fast in your head.
1/3 of 9 = 9/3=3x1=3
2/5 of 25= 25/5=5x2=10
Take the denominator (bottom part of a fraction) and divide your whole number by it. Then multiply that by the numerator (top part of a fraction).