The oldest Hindu texts including mathematics can be dated from the first centuries A.C, but are probably much older and have been influenced by Greeks, Babylonians, and Chinese. These texts indicate that ancient Indians used a decimal number system and had separate symbols for $1,\ldots,9,10,20,\ldots,100,200,\ldots,1000,2000,\ldots.$ In the Sulbasutras, containing mathematical recipes to solve religious problems related to building altars. These problems contained formulas for the areas of squares, rectangles, their diagonals, as well as comparisons between the areas of squares and circles.