Answer
42
Work Step by Step
Use the factor tree to find the prime factorization for each number:
7 and 2 are factors of 14. Both are prime. So, 7x2 is the prime factorization for 14.
3 and 7 are factors of 21. Both are prime. So, the prime factorization of 21 is 3x7.
Use each prime number the greatest number of times it appears in either numbers' prime factorization.
2 appears the most (1 time) in 14, 3 appears the most (1 time) in 21, and 7 appears the same amount of times (1 time) in both 14 and 21.
Therefore, the LCM is 2x3x7 which equals 42.
