What is the greatest common factor of 90 and 125?
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Detailed Answer:Greatest Common Divisor explained here

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What is the GCF of 90 and 125?
The first step to find the gcf of 90 and 125 is to list the factors of each number. The factors of 90 are 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45 and 90. The factors of 125 are 1, 5, 25 and 125. So, the Greatest Common Factor for these numbers is 5 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(90, 125).
In this case we have:
 The factors of 90 (all the whole numbers that can divide the number without a remainder) are 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45 and 90;
 The factors of 125 are 1, 5, 25 and 125.
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 90 and 125 is 5. The GCF is the largest common positive integer that divides all the numbers (90, 125) 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