have somebody's number
have (got) (one's) number
To understand or know someone or something well enough to anticipate what they will do. That team is impossible to beat—they've had our number since 2006! Oh, don't worry, I've got his number—he's a typical brat.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
have somebody’s ˈnumber(informal) really understand what type of person somebody is and what they plan to do: Don’t worry, I’ve got his number. I shall be very careful in any business I do with him. ♢ You can’t fool me, you know. I’ve got your number.
Farlex Partner Idioms Dictionary © Farlex 2017