By what number should 12348 be multiplied to make it a perfect square?
2023
By what number should 12348 be multiplied to make it a perfect square?
- A.
7
- B.
11
- C.
13
- D.
19
Show answer & explanation
Correct answer: A
A whole number is a perfect square exactly when every prime in its factorization has an even exponent (the perfect-square test from the Fundamental Theorem of Arithmetic). To turn a non-square integer into a perfect square using the smallest possible multiplier, factorize it and multiply by exactly the primes whose exponents are currently odd, so each odd exponent becomes even.
Factorize 12348 into primes: 12348 = 22 × 32 × 73.
Check each exponent for evenness: the exponents of 22 and 32 are already even (2 and 2), but the exponent of 7 is 3, which is odd.
Multiply by 7 to raise 73 to 74, making every exponent even: 12348 × 7 = 22 × 32 × 74.
So the required multiplier is 7.
Cross-check: 22 × 32 × 74 = (2 × 3 × 72)2 = 2942, and 294 × 294 = 86436 = 12348 × 7, confirming the product is indeed a perfect square.