Off the top of my head and according to what he meant by single number: - As a single entity: I usually think in decimal so you could write a "single" decimal

Off the top of my head and according to what he meant by single number: - As a single entity: I usually think in decimal so you could write a "single" decimal number (e.g. 234) and convert it to binary and the 1 and 0 character mean Yes / No. - As a single character: You could just write a random character (e.g. ॐ ), specifying that is has to be interpreted as a number in Base N+1 and ॐ + 1 = 10. This is useless though.