need to find darma name

hello

need to remember the drama name forgot it if its Chinese or korean just  remember this scene

the ML tell The FM to remember to some kind of number for focus  on the target to not get nervous while 

becoming the police officer i think FL wanted to become the police officer

thanks

 Div:

Hi! I think you're referring to Hello, the Sharpshooter (ep 10)

thank but its not that one i think the ML said whenever he got nervou he remembers those number it was long number i think hes police officer  or swat member cant remember excatly