We call them Arabic Numerals, but our numbers actually find their origins in the history of the Hindus of India. They have changed greatly over the centuries, passing first to the Arabs of the Middle East and finally to Europe in the Middle Ages, and are now the most commonly used numbers throughout the world.
The Basis of Our Number System
The number system that we use today is a place value decimal system. What that means is that not only the number, but the placement of the number is important. Take a look at the number 536. This incorporates three numerals: 5, 3 and 6. Because we use a place value system, we know that the 5 does not stand just for 5, it means 500. The 3 stands for 30, and the 6, being in the ones place, is just 6. Rather than writing 500 + 30 + 6, our system allows us to write it simply as 536.
Our system is also decimal, because it is based upon increments of 10. We have 10 numerals in our system: 1, 2, 3, 4, 5, 6, 7, 8, 9 and 0. We count 1 through 9, then move to the next level with 10. Then we go up in the ones place through 9 before moving to the next 10s place (20). Each place value in the system is ten times the value of the one before it. (Ones, then tens, then hundreds, thousands and so on).
The vital element in making this system work is the development of the concept of zero. Aside from the Maya of Central America, the only group to develop the concept of zero was the Hindu peoples of India.
When exactly the Hindus first began using a place value decimal system which incorporated zero is not certain. They were certainly using such a system in 400 CE, where we first find inscriptions of 0. (The Maya were using 0 before this time, and were the first to use it.)
By the 7th century CE a fully developed place value decimal system was in place. The Brahmasphutasiddhanta (Opening of the Universe) was composed in 628 CE, and demonstrated a full set of Indian numerals including 0.
Although the 0 is not shown until 400 CE, Indian scripts for numerals first start appearing in the 1st century. There were two major scripts: the Brahmi and the Kharosthi scripts. It is from the Brahmi script that our own numbers originate.
The symbols for 1, 2 and 3 in the Brahmi scripts were originally lines: one line for 1, two lines for 2 and 3 lines for 3, drawn horizontally. Over time these lines began to be connected together (and the one line rotated 90 degrees so it would be vertical). When you look at our own 2 and 3 today, you can see how the 2 was originally 2 lines which were joined with a line through the middle, and the 3 composed of 3 lines connected.
After the number 3, different symbols were used to represent these numbers. Most of the symbols used in the Brahmi script are similar to the numerals that we use today.