The GCF is 14.
The GCF is 4.
* One method is to factor each number into prime factors, and see what factors they have in common. 210 = 2x105 = 2x5x21 = 2x5x3x7, or 2x3x5x7. 308 = 2x154 = 2x2x77 = 2x2x7x11. The GCF is 2x7 = 14. * Another method (more efficient, especially for larger numbers) is Euclid's algorithm. In this case for example, the greatest common factor of 308 and 210 is the same as the greatest common factor of 210 and 98. This latter number is the remainder of the division of 308 by 210. Continue until one of the numbers is zero. In that case, the other one is the greatest common factor. 308/210 = 1, remainder 98 210/98 = 2, remainder 14 98/14 = 7, remainder 0. The previous remainder (14) is the GCF.
210 and 420 have a GCF of 210.
Since 210 is a factor of 420, it is automatically the GCF.
The GCF is 4.
The greatest common factor (GCF) of 126 and 308 is 14.
The GCF is 6.
The GCF is 70.
The GCF is 42.
The GCF is 15.
The GCF is 105.