ADVERTISEMENT
  About the SA Blog Network

Posts Tagged "the simpsons"

Roots of Unity

How the Simpsons (And You) Can Multiply by Seven Using Your Fingers

3 times 7 is...25? What?

When I tutored elementary school math, one of my favorite things to show the kids was how to multiply by 9 using their fingers. (I apologize, but this trick assumes that you have five fingers on each hand. Later you’ll see how to adapt it if you have nonstandard hands.) Here’s how the finger rule [...]

Keep reading »

More from Scientific American

Scientific American Dinosaurs

Get Total Access to our Digital Anthology

1,200 Articles

Order Now - Just $39! >

X

Email this Article

X