NCERT Figure it Out 1 - Q2 - A Story of Numbers
Question: Method 2 uses letters a-z for 1-26. One extension uses 'aa' for 27. How can you extend the system to represent all numbers?
Answer: After a..z, continue with longer strings (e.g. aa, bb, ..., zz, then aaa, ...) in a fixed order so every natural number gets a name.
Full step-by-step NCERT solution with diagrams on Something by Zero.