Question

A rope with knotted cords that served as a calculator

Answer 1

A rope with knotted cords, which could have been of different lengths and colors, was primarily used as a calculator. This ancient calculation tool was used by Inca, called quipu. It was also used for recording and storing information. Quipu consisted of ropes that were knoted and represented numbers. The smallest number in, for example, the two-digit number 26 would be represented by six touching knots at the free end of the rope, and two touching knots with a distance in relation to the first six would come on top of it on the hung rope.

Answer 2

I believe the answer is quipu. I hope this helps.   :)