4. As decimal number system has 10 digits, it is called system.

1.	4. As decimal number system has 10 digits, it is called system.
Answer» Decimal system, also called Hindu-Arabic number system or Arabic number system, in mathematics, positional NUMERAL system employing 10 as the base and requiring 10 different NUMERALS, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. It also REQUIRES a dot (decimal point) to represent decimal fractions

Discussion