Find the smallest square number that is divisible by each of the numbers 5, 15 and 45.


Given: 5, 15, 45

To find: We need to find the smallest square number that is divisible by each of the no 5, 15, and 45.

Solution: 

First we need to find the LCM of the given numbers i.e. 5, 15 and 45.

Now,

Writing all the numbers as a product of their prime factors:

Prime factorization of 5:

  • 5 = 51

Prime factorization of 15:

  • 3 $\times $ 5 = 31 $\times $ 51

Prime factorization of 45:

  • 3 $\times $ 3 $\times $ 5 = 32 $\times $ 51

Highest power of each prime number:

  • 32 , 51

Multiplying these values together:

  • 32 $\times $ 51 = 45

Thus,

LCM(5, 15, 45) = 45

We know that in a perfect square all the prime factors of that number are in pairs. So, we need to multiply 45 with 5 to make it a perfect square.

45 $\times $ 5 = 225

So, the smallest square number that is divisible by each of the no 5, 15 and 45 is 225.

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Updated on: 10-Oct-2022

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