ncr Combinatorial Number Calculation npr Arrangement Number Calculation The way to use it is to first enter its corresponding subscript on the calculator, then press ncr or npr, and finally enter the superscript. e.g., 4ncr3, which stands for.

Origin and development

Original development

Calculators were the earliest tools for calculating e.g. Chipu (Quipu or khipu) was an ancient Inca method of knotting ropes for counting or recording history. It was made up of knots of many colors.

There was also the Antikythera device of the ancient Greeks and the Chinese abacus. One of the earliest calculation tools used in ancient China was called the chip, also known as the counting chip. This kind of counting chip is mostly made of bamboo, but there are also used wood, animal bone as a material. About two hundred and seventy pieces in a bundle, in a cloth bag can be carried around.

Till today is still in use bead abacus, is another invention in the field of ancient Chinese computing tools, bead abacus in the Ming Dynasty has been almost the same as the modern bead abacus.