What is 55 multiplied by 25?

Answer 1

Here's how to do this in your head:

55 X 25 = (10 + 10 + 10 + 10 + 10 + 10/2) X 25 = (10 X 25) + (10 X 25) + (10 X 25) + (10 X 25) + (10 X 25) + (10/2 X 25) = 250 + 250 + 250 + 250 + 250 + 250/2 = 500 + 500 + 250 + 125 = 1250 + 125 = 1375

You can expand this method out to three, four, even five digit numbers, and if you practice enough, you'll soon be impressing all of your friends around the D & D table with your calculator-like brain!

If you know the FOIL method (First, Outer, Inner, Last) you can make this even easier. Pay attention because we're getting pretty advanced now:

55 X 25 = (50 + 5) X (20 + 5) = 50 X 20 (the first terms) + 50 X 5 (the outer terms) + 5 X 20 (the inner terms) + 5 X 5 (the last terms) = (50 X 10 X 2) + (50 X 10 / 2) + (5 X 10 X 2) + (5 X 5) = (500 X 2) + (500/2) + (50 X 2) + 25 = 1000 + 250 + 100 + 25 = 1375.

If you're comfortable with multiplying and dividing by 2, which you should be, what's written above takes approximately 5 seconds to do in your head.