The discussion of the importance of numbers in everyday life and how "Arabic" numbers and algebra changed the world is worthy of a book – or at least a separate article. However, the short story is that numbers were represented as hash marks (i.e. ||| for 3) or glyphs with certain value representations (i.e. Roman Numerals where X represents 10). Either way, you had to count, add and subtract the different symbols to arrive at the value involved. That alone could be overwhelming for the math challenged! Then the system of representing numbers that we use today was invented, probably in India. There are ten symbols representing 0-9, placed in columns. Starting from the right, when you run out of symbols to use in one column (that is reach 9 and need to add one more); you reset it to 0 and go to the next column to the left and add one there. Thus, even in languages that are written right to left (i.e. most Middle Eastern languages), the digit with the highest value goes on the left and the digit with the lowest value goes on the right. Don't worry if the preceding is confusing to you, these are the numbers we use every day; all you really need to remember is that you can view our number system as a right to left system too, even though we usually read numbers from left to right. If you remember learning math in columns in elementary school, where you start on the right and work to the left, you understand everything you need.
These numbers came to Europe through the introduction of Algebra from the Arab world. This is why we refer to our numbers as “Arabic numbers” (versus “Roman numerals”) - again, stuff we don't normally think of after elementary school. However, in spite of the fact that we call them “Arabic Numbers”, much of the Middle East uses different symbols for the digits 0-9. These are called the Hindi numbers – but actually vary a little bit from Hindi depending on the language used. The various digits are shown below:
You will also see Latin digits. In Biblical Hebrew (Modern Hebrew uses the Latin digits), Koine Greek (used during Roman occupation in much of the Middle East), and older, non-mathematical uses of Arabic each letter has a numeric value – just like the Roman Numerals you learned in elementary school. Numbers are determined by adding up the quantities each letter represents. With this, you should be able to decipher any number you see in the Middle East or documents in Middle Eastern languages.
"Arabic numerals." Wikipedia, The Free Encyclopedia. Detailed information on the history of the Arabic numerals. 18 Sep 2006, 02:31 UTC. Wikimedia Foundation, Inc. 20 Sep 2006 <http://en.wikipedia.org/w/index.php?title=Arabic_numerals&oldid=76339928>.
Microsoft Corporation. "Digits Support in Microsoft Windows XP." Microsoft Products and Arabic Support ver. 3.0. Digits used in different Middle Eastern languages and how to display them in Windows XP. 2005. Microsoft Corporation. 20 Sep 2006 <http://www.microsoft.com/middleeast/arabicdev/windows/winxp/DigitsSupport.aspx>.