Rack brains.
/ræk breɪnz/
Rack brains.
/ræk breɪnz/
To "Rack brains" means to think very hard or strain mentally to recall or solve something. The imagery is almost physical, suggesting a wringing out of one’s mind to extract ideas or memories. It’s about deep mental exploration.
I've been racking my brains trying to remember where I left my keys.
The person is trying very hard to recall the exact location of the lost keys.
He racked his brains for hours trying to solve the puzzle.
He spent a lot of mental effort attempting to find a solution to the complex problem.
She's been racking her brains all day about how to fix the error in the report.
She spent the entire day thinking intensely to correct a mistake found in her report.