Question
The work that Yi did to find the greatest common factor of 42 and 63 is shown below.
Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 63: 1, 7, 9, 63
The greatest common factor is 7.
What is Yi’s error?
Yi did not list all the factors of 63.
Yi listed multiples for each number instead of factors.
Yi did not list all the factors of 42.
Yi found the least common multiple.
Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 63: 1, 7, 9, 63
The greatest common factor is 7.
What is Yi’s error?
Yi did not list all the factors of 63.
Yi listed multiples for each number instead of factors.
Yi did not list all the factors of 42.
Yi found the least common multiple.
Answers
GPT-4o mini
The error in Yi’s work is that **Yi did not list all the factors of 63.**
The factors of 63 should be 1, 3, 7, 9, 21, and 63, rather than just 1, 7, 9, and 63. Because of this incomplete list of factors, Yi arrived at the incorrect greatest common factor (GCF) of 7. The actual GCF of 42 and 63 is 21, which is the highest number that appears in both complete lists of factors.
The factors of 63 should be 1, 3, 7, 9, 21, and 63, rather than just 1, 7, 9, and 63. Because of this incomplete list of factors, Yi arrived at the incorrect greatest common factor (GCF) of 7. The actual GCF of 42 and 63 is 21, which is the highest number that appears in both complete lists of factors.