number-to-register

number-to-register is an interactive compiled Lisp function in `register.el'.

It is bound to C-x r n.

(number-to-register NUMBER REGISTER)

Store a number in a register.
Two args, NUMBER and REGISTER (a character, naming the register).
If NUMBER is nil, a decimal number is read from the buffer starting
at point, and point moves to the end of that number.
Interactively, NUMBER is the prefix arg (none means nil).

Interactively, reads the register using `register-read-with-preview'.