What base did the egyptian number system use?

Answer 1

The ancient Egyptian numeric system did not operate on a "base" system such as we use today; it is true that the system used units, tens, hundreds, thousands, ten thousands and so on, but each of these numeric values was represented by completely differentnumerals.

So in our own system the number 538 is not the same as 835, but in the Egyptian system it could be identical - because it was written with the signs for 5x100, 3x10 and 8x1 and it would mean the same if written in reverse (8 units, 3 tens and 5 hundreds).

This explains why no zero was required - simply leaving out one kind of numeric sign meant the absence of that particular value.