In Section 1-9 we considered briefly the little that is known concerning the part played by the Hindus in the development of our present positional numeral system. We shall now give some account of Hindu methods of computing with this system. The key to an understanding of the algorisms that were elaborated lies in a realization of the writing materials which were at the disposal of the calculators.According to the German historian H. Hankel, they generally wrote either upon a small blackboard with a cane pen dipped in a thin white paint which could easily be rubbed