Question

What is the greatest common factor of 91, 26, 52, and 78?

Answer 1

To find the greatest common factor (GCF) of the numbers 91, 26, 52, and 78, we'll begin by determining the prime factorization of each number.

1. **Prime factorization of 91:**
- 91 = 7 × 13

2. **Prime factorization of 26:**
- 26 = 2 × 13

3. **Prime factorization of 52:**
- 52 = 2^2 × 13

4. **Prime factorization of 78:**
- 78 = 2 × 3 × 13

Next, we will list the prime factors of each number:

- Prime factors of 91: 7, 13
- Prime factors of 26: 2, 13
- Prime factors of 52: 2, 13
- Prime factors of 78: 2, 3, 13

Now, we find the common prime factors among all four numbers. The only prime factor that is common to all four numbers is **13**.

Thus, the GCF of 91, 26, 52, and 78 is:
\[
\boxed{13}
\]