Hindu-Arabic numerals are the digits 1 to 9 in use today. Before their introduction to Europe in the 13th century, Roman numerals were used, which were not well suited for performing numerical calculations, such as multiplication and division. One of the major factors in the expediency of the new number system, was the inclusion of a symbol to represent the value zero. This digit was called ciphre. The other factor was the positional system which gave the digits higher values, the farther towards the left they were written in a composite number.
Thus, in the number 387, the right-most digit signiefies the value seven, the second one from the right signiefies the value eighty and the third one three hundred. But this was not so easy to understand for a mind only accustomed to the Roman numerals. The Art of Algorismus then consisted in learning to apply cerain rules for multiplying, dividing, and calculating the square and cubic roots of numbers written in this fashion.
These numbers are oft referred to as Arabic numerals. But it was actually the mathematicians on the Indian subcontinent who invented them. The Arabs learned about them and their use from the Hindus, and transmitted them to Europe through texts writen in Arabic, that became translated to Latin.