The evolution of the Hindu-Arabic numbers was not a straight line from India to Arabia and on to Europe. In between, the Arab cultures had more than one number system to contend with, including at least three different types of arithmetic: finger-reckoning arithmetic (counting on fingers), a sexagesimal system with numbers written in letters of the Arabic alphabet, and Indian numeral arithmetic.

The evolution of the Hindu-Arabic numbers continued throughout time and includes some good reasons for why our numbers look as they do today. For example, historians believe that between 970 and 1082, the numbers 2 and 3 changed significantly, rotating 90 degrees from their original written position. This is thought to be due to how scribes worked: Sitting cross-legged, they wrote on a scroll they wound from right to left across their body. This caused them to write from top to bottom, not our usual right to left; the script was then rotated when the scroll was read.

Different cultures generally employed one of two strategies when creating symbols for numbers: multiple marks that indicated single numbers or multiples of fives or tens (e.g., Babylonian, Egyptian, Mayan), or a more abstract system using a single symbol for the numbers one through nine, with numbers then being shifted over one or more places to indicate multiples of ten, hundreds, etc. (e.g., Hindu, Hindu-Arabic).