I'd never thought about it in this way before but the idea of writing a number as a decimal (or other) string of numerals, bears some resemblance to a Fourier t

I'd never thought about it in this way before but the idea of writing a number as a decimal (or other) string of numerals, bears some resemblance to a Fourier transform. Think of the components of a written number: ones, tens, hundreds etc which have a repeating pattern. Digits are inherently periodic. Not too far from periodic basis functions. Both involve breaking something down into periodic components, and reversing the process by adding up the components.