What is the GCF of 15 and 42?
Understand the Problem
The question is asking for the greatest common factor (GCF) of the numbers 15 and 42, which requires identifying the largest number that divides both 15 and 42 without leaving a remainder.
Answer
The greatest common factor is $3$.
Answer for screen readers
The greatest common factor of 15 and 42 is $3$.
Steps to Solve
- List the factors of each number
First, find all the factors for both 15 and 42.
- The factors of 15 are: 1, 3, 5, 15.
- The factors of 42 are: 1, 2, 3, 6, 7, 14, 21, 42.
- Identify the common factors
Now, determine which factors are common between the two lists.
- The common factors are: 1, 3.
- Find the greatest common factor
Among the common factors, identify the largest one.
- The greatest common factor is: 3.
The greatest common factor of 15 and 42 is $3$.
More Information
The GCF is the largest number that divides both numbers without a remainder. This concept is useful in simplifying fractions, finding equivalent ratios, and solving problems involving divisibility.
Tips
- Overlooking factors: Sometimes people forget to list all the factors of each number.
- Incorrect identification of greatest factor: Failing to choose the largest common factor from the list.
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