Any number which is an exact divisor of  a given number is called a factor of the given number.
    For example factor of 6 are 1,2,3 and 6
    Important results :
    (a)     1 is a factor of every number.
    (b)     Every number is a factor of itself.
    (c)     Every factor of a number is always equal to or less than the number.
    (d)     Every number has a finite number of factors.