rack one's brain

/ɹˈak wˈɒnz bɹˈeɪn/

/ɹˈæk wˈʌnz bɹˈeɪn/

to rack one's brain

to think hard or make a great effort to remember or solve something

Examples

1. And you can rack your brain, how does it relate to atoms?

2. I've been racking my brain, but I can't remember his name.

3. We racked our brains but we couldn't come up with a solution.

4. He racked his brains all weekend trying to think of a solution to the problem.