REAL NUMBERS, R

3. Natural Numbers, N

The natural numbers are the positive integers. We denote the set of natural

numbers by N; hence N = {1,2,3…..}

The natural numbers were the first number system developed and were used

primarily, at one time, for counting. Notice the following relationship between

the above numbers systems:

NZQR

The natural numbers are closed only under the operation of addition and multiplication. The difference and quotient of two natural numbers needed not be a natural number.

The prime numbers are those natural numbers p, excluding 1, which are only divisible 1 and p itself. We list the first few prime numbers:

2,3,5,7,11,13,17,19…