GCD of 102 and 156
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Detailed Answer: Greatest Common Divisor explained here

You have reached us maybe looking for answers to the questions like: GCD of 102 and 156 or what is the highest common factor (HCF) of 102 and 156?
What is the GCF of 102 and 156?
The first step to find the gcf of 102 and 156 is to list the factors of each number. The factors of 102 are 1, 2, 3, 6, 17, 34, 51 and 102. The factors of 156 are 1, 2, 3, 4, 6, 12, 13, 26, 39, 52, 78 and 156. So, the Greatest Common Factor for these numbers is 6 because it divides all them without a remainder. Read more about Common Factors below.
See also:
How to find the Greatest Common Factor
GCF example:
The first step is to find all divisors of each number. For instance, let us find the gcf(102,156).
In this case we have:
 The factors of 102 (all the whole numbers that can divide the number without a remainder) are 1, 2, 3, 6, 17, 34, 51 and 102;
 The factors of 156 are 1, 2, 3, 4, 6, 12, 13, 26, 39, 52, 78 and 156.
The second step is to analyze which are the common divisors. It is not difficult to see that the 'Greatest Common Factor' or 'Divisor' for 102 and 156 is 6. The GCF is the largest common positive integer that divides all the numbers (102,156) without a remainder.
The GCF is also known as:
 Greatest common divisor (gcd);
 Highest common factor (hcf);
 Greatest common measure (gcm), or
 Highest common divisor