"One equals two" growled the mass of zombies in the distance. "One equals two."

The first put down the shotgun. "I've got this one," he said, picking up the megaphone.

"If you're sure," said the second.

"I'M SURE."

The second covered his ears.

"SORRY. I mean, sorry." The first redirected the megaphone towards the horde. "PROVE IT!"

"Let $x=y$" they grumbled.

"CONSIDER IT LET"

"Multiply by $x$, so $x^2 = xy$."

"AGREED"

"Take away $y^2$, so $x^2 - y^2 = xy - y^2$."

"NOLO CONTENDERE."

"Nolo contendere?" said the second.

"I don't dispute it," said the first.

"Now factorise," groaned the zombies. "$(x+y)(x-y) = y(x-y)$."

"OK." Aside "Can you ready the shotgun, please."

"Divide by $(x-y)$..."

Bang. Bang.

"YOU CAN'T DIVIDE BY ZERO, ZOMBIES. Good shot."

"Good shootdown."

Fistbump.

## Colin

Colin is a Weymouth maths tutor, author of several Maths For Dummies books and A-level maths guides. He started Flying Colours Maths in 2008.
He lives with an espresso pot and nothing to prove.