Common Factor
Common Factor : A number which is a factor (or sub-multiple) of each of the given numbers, e. g. of the numbers 10, 15 and 25, 5 is a common factor. The highest common factor is the greatest possible number dividing into each of several numbers having more than one factor. Thus 10 is the H. C. F. of 30, 50 and 120, whilst 2 and 5 are ordinary factors