Answer:
GCF = 6; sum = 6(1 +3)
Explanation:
You want the greatest common factor of 6 and 18.
GCF
The greatest common factor is the largest factor common to both numbers. Here, we can factor the numbers as ...
6 = 6·1
18 = 6·3
The factor 6 is common to both numbers. (Other numbers, such as 1, 2, and 3 are also common factors, but 6 is the largest.)
The GCF is 6.
In terms of the GCF, the sum can be written ...
6 +18 = 6(1 +3)
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Additional comment
If the smaller number is not a factor of the larger, then the next value to check is the difference between the larger and smaller.
Euclid's algorithm tells you the remainder from division of the larger by the smaller will be zero when the divisor is the GCF. Otherwise, the remainder can be used to replace the larger number for trying again.
Here, 18/6 = 3 r 0, so 6 is the GCF.