Numberphile revived an ancient multiplication trick—halves and doubles—also called Egyptian or Russian math, where you repeatedly halve one number and double the other. After crossing out rows with ...

Lindsey Ellefson is Lifehacker’s Features Editor. She currently covers study and productivity hacks, as well as household and digital decluttering, and oversees the freelancers on the sex and ...

Some of the Capital One offers mentioned below are not currently available. Terms apply to American Express benefits and offers. Visit americanexpress.com to learn more. There are a lot of perks that ...

As a long-time Windows geek, I’ve always loved and relied on keyboard shortcuts. They’re incredible! Like a collection of secret handshakes that can quickly perform useful tasks and dramatically speed ...