Question

What is the greatest common factor (GCF) of 42, 63, 84, and 126?

A) 6
B) 7
C) 14
D) 21

Answer 1

The greatest common factor (GCF) of 42, 63, 84, and 126 is 21, as it's the highest number that divides into all of them without any remainder.

Step-by-step explanation:

The greatest common factor (GCF) of 42, 63, 84, and 126 is determined by finding the highest number that can divide into all of these numbers evenly. To find the GCF, we list the factors of each number:

• 
  
• Factors of 42 are 1, 2, 3, 6, 7, 14, 21, 42
• 
  
• Factors of 63 are 1, 3, 7, 9, 21, 63
• 
  
• Factors of 84 are 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
• 
  
• Factors of 126 are 1, 2, 3, 6, 7, 9, 14, 18, 21, 42, 63, 126

Looking at the factors they have in common, the highest one is 21. Therefore, the GCF of 42, 63, 84, and 126 is 21 (option D).