Is 2100 prime or composite

Answer 1

A Prime number is one who's only factors are One and Itself. Sometimes people will say a number is 'divisible by X', which means that X is a factor of the number.

There are several tests for certain factors that you can do quickly, if you memorize them. For example, 2100 has several factors that I can spot without doing any division: It has zero in the ones digit. This tells me that it's divisible by 5, also 0 in ones digit tells me that it's even (divisible by 2). The 'sum of the digits' is a multiple of three, so the number is also a multiple of three (2 + 1 + 0 + 0 = 3).

Answer 2

composite