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Solution - Least common multiple (LCM) by prime factorization

65,520
65,520

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 90

Tree view of the prime factors of 90: 2, 3, 3 and 5

The prime factors of 90 are 2, 3, 3 and 5.

3. Find the prime factors of 91

Tree view of the prime factors of 91: 7 and 13

The prime factors of 91 are 7 and 13.

4. Find the prime factors of 280

Tree view of the prime factors of 280: 2, 2, 2, 5 and 7

The prime factors of 280 are 2, 2, 2, 5 and 7.

5. Find the prime factors of 455

Tree view of the prime factors of 455: 5, 7 and 13

The prime factors of 455 are 5, 7 and 13.

6. Build a prime factors table

Determine the maximum number of times each prime factor (2, 3, 5, 7, 13) occurs in the factorization of the given numbers:

Prime factorNumber16 90 91 280 455 Max. occurrence
2410304
3020002
5010111
7001111
13001011

The prime factors 5, 7 and 13 occur one time, while 2 and 3 occur more than once.

7. Calculate the LCM

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

LCM = 2222335713

LCM = 24325713

LCM = 65,520

The least common multiple of 16, 90, 91, 280 and 455 is 65,520.

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.