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What is the smallest number divisible by 1 9?

Published in Mathematics 1 min read

The question is ambiguous. It could mean:

  1. What is the smallest number divisible by both 1 and 9?
  2. What is the smallest number divisible by all integers from 1 to 9 (inclusive)?

We will answer both interpretations.

Interpretation 1: Smallest Number Divisible by 1 and 9

The smallest number divisible by both 1 and 9 is 9. Any number divisible by 9 is also divisible by 1.

Interpretation 2: Smallest Number Divisible by 1 Through 9

The smallest number divisible by all the integers from 1 to 9 is their Least Common Multiple (LCM). To find the LCM, we can use prime factorization.

  • 1 = 1
  • 2 = 2
  • 3 = 3
  • 4 = 2 x 2 = 22
  • 5 = 5
  • 6 = 2 x 3
  • 7 = 7
  • 8 = 2 x 2 x 2 = 23
  • 9 = 3 x 3 = 32

To find the LCM, take the highest power of each prime number that appears in the factorizations:

  • 23 = 8
  • 32 = 9
  • 5 = 5
  • 7 = 7

Multiply these together: 8 x 9 x 5 x 7 = 2520.

Therefore, the smallest number divisible by all integers from 1 to 9 is 2520.

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