What function?

[excelvn]

Cell A1= M001
Cell A2= M002
.....
Cell A12=M012
.....
================
Cell B1 = M001 +1 = *M002*
Cell B2 = M002 +1 = *M003*

Cell B12 = M012+1 = *M013*

I would like the function and copy down to more rows.
Please help me soon.
Thank

 

[Arvi Laanemets]

Hi

A1="M" & TEXT(ROW(),"000")
, and copy down