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Which is the smallest number divisible by both 9 and 12?

Published in Least Common Multiple 2 mins read

The smallest number divisible by both 9 and 12 is 36.

Understanding the Least Common Multiple (LCM)

The question asks for the smallest number that both 9 and 12 can divide into without leaving a remainder. This is known as the Least Common Multiple (LCM). The LCM is the smallest positive integer that is a multiple of two or more given integers.

Here's a brief breakdown using the given reference:

According to the provided information, the LCM of 9 and 12 is 36. This is the smallest number that is evenly divisible by both 9 and 12.

How to Find the LCM:

Several methods can be used to find the LCM. Here are a few examples:

  • Listing Multiples: You could list out multiples of each number until you find a common one.
    • Multiples of 9: 9, 18, 27, 36, 45...
    • Multiples of 12: 12, 24, 36, 48...
    • The first common multiple in both lists is 36.
  • Prime Factorization: Another method involves breaking down the numbers into prime factors.
    • Prime factors of 9: 3 x 3 or 3²
    • Prime factors of 12: 2 x 2 x 3 or 2² x 3
    • To find the LCM, take the highest power of each prime factor that appears: 2² x 3² = 4 x 9 = 36.
  • Using a Formula: For two numbers, you can use the formula: LCM (a, b) = (|a b|) / GCD(a, b), where GCD is the Greatest Common Divisor. The GCD of 9 and 12 is 3. So, LCM(9,12) = (9 12)/3 = 108 / 3 = 36.

Example:

Let's check that 36 is divisible by both 9 and 12:

  • 36 ÷ 9 = 4
  • 36 ÷ 12 = 3

As you can see, 36 is perfectly divisible by both numbers without a remainder, and it’s the smallest number with this property.

Conclusion

Therefore, based on the information provided and established mathematical principles, the smallest number divisible by both 9 and 12 is 36.

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