What is the ancient Egyptian symbol for zero?

The ancient Egyptian numeric system has no zero, nor does it need one. Because there are completely different signs for units, tens, hundreds, thousands, ten thousands, hundred thousands and so on, simply leaving out one type of sign expresses the absence of that number - no zero is required.

In writing, the idea of "nothing" or "zero" is expressed by the Word nfr but this is not used in arithmetic calculations.