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Solution - Least common multiple (LCM) by prime factorization

20,592
20,592

Step-by-step explanation

1. Find the prime factors of 16

Tree view of the prime factors of 16: 2, 2, 2 and 2

The prime factors of 16 are 2, 2, 2 and 2.

2. Find the prime factors of 18

Tree view of the prime factors of 18: 2, 3 and 3

The prime factors of 18 are 2, 3 and 3.

3. Find the prime factors of 22

Tree view of the prime factors of 22: 2 and 11

The prime factors of 22 are 2 and 11.

4. Find the prime factors of 13

13 is a prime factor.

5. Build a prime factors table

Determine the maximum number of times each prime factor (2, 3, 11, 13) occurs in the factorization of the given numbers:

Prime factorNumber16 18 22 13 Max. occurrence
241104
302002
1100101
1300011

The prime factors 11 and 13 occur one time, while 2 and 3 occur more than once.

6. Calculate the LCM

The least common multiple is the product of all factors in the greatest number of their occurrence.

LCM = 2222331113

LCM = 24321113

LCM = 20,592

The least common multiple of 16, 18, 22 and 13 is 20,592.

Why learn this

The least common multiple (LCM), sometimes called the lowest common multiple or least common divisor, is helpful for understanding the relationships between numbers. For example, if it takes Earth 365 days to orbit the sun and it takes Venus 225 days to orbit the sun and both are in perfect alignment at the time this scenario is given, how long will it take for Earth and Venus to align again? We can use LCM to determine that the answer would be 16,425 days.

LCM is also a very important part of many mathematical concepts that also have real-world applications. For example, we use LCMs when adding and subtracting fractions, which we use quite frequently.