Explanation:
Using box method to find GCF.
We take all numbers at top pf box and start with 2 first row of box
Fill 1st row by dividing each number by 2. If number is not divisible change the number "2"
Example: Find GCF of 24 and 36
24 36
2 12 18 --------- 1st row
2 6 9 ----------2nd row
2 3 X ---------- 3rd row ( 9 is not divisible by 2. Now we take 3 )
3 2 3 ---------- 3rd row
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24 36
2 12 18 --------- 1st row
2 6 9 ----------2nd row
3 2 3 ---------- 3rd row
If we get any column with prime number. we stop here.
Please see attachment for box.
Now we multiply all the number in first column.
2 x 2 x 3 = 12
So, GCF of 24 and 36 is 12