How to Multiply Numbers Quickly Using the Associative Property
Multiply faster!
Jason Marshall, PhD
Thanks to the associative property of multiplication, instead of simply multiplying a list of numbers in the order they’re written from left-to-right, you have the freedom to multiply the numbers in any order you want. Why would you ever want to do that? Because sometimes it makes things easier. For example, in the problem 2x3x4x5, one option is to simply do the multiplication working from left-to-right: 2×3=6, then 6×4=24, and finally 24×5=120.
That’s not too difficult in this case (although it would be worse in a more complex problem), but it’s slower and more work than it has to be. Instead, let’s use the fact that the associative property allows us to multiply numbers in any order we’d like to solve the problem like this: 2×5=10, 3×4=12, and then 10×12=120. Do you see why that’s a better way? Because multiplying numbers by 10 (or by any multiple of 10) is always faster and easier!
For more, see What Is The Associative Property?
Multiplication Symbol image courtesy of Shutterstock
About the Author
Jason Marshall is the author of The Math Dude’s Quick and Dirty Guide to Algebra. He provides clear explanations of math terms and principles, and his simple tricks for solving basic algebra problems will have even the most math-phobic person looking forward to working out whatever math problem comes their way.