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Question

If LCM of 'a' and "a+2" is 1300. Find the LCM of "a" and a+1.

The correct answer is
2550

To solve the given problem, we need to find the LCM (Least Common Multiple) of two numbers: \( a \) and \( a+1 \), given that the LCM of \( a \) and \( a+2 \) is 1300.

Let's first establish key relationships:

  1. The LCM of two numbers \( a \) and \( b \) is calculated as: \(LCM(a, b) = \frac{a \cdot b}{GCD(a, b)}\) where \( GCD \) is the greatest common divisor.
  2. Given \( LCM(a, a+2) = 1300 \), it implies that \( a(a+2) \)/GCD(a, a+2) = 1300.

Now, let's analyze the divisibility that fits the LCM condition of 1300:

  1. 1300 can be factored into prime factors: \(1300 = 2^2 \cdot 5^2 \cdot 13\)
  2. Since \( a \) and \( a+2 \) are consecutive even numbers or both odd, their difference is 2. Therefore, their greatest common divisor will be 1 if they are consecutive odd numbers, and 2 if they're even numbers.

To find \( a \), we test possible divisors:

  1. Consider \( a = 25 \). Then \( a+2 = 27 \).
  2. Calculate \( \frac{25 \times 27}{GCD(25, 27)} = 1300 \). Simplification gives: \( \frac{675}{1} = 1300 \). Here this doesn't hold since GCD is 1 for prime-like \( a, a+1\).
  3. Alternatively, pick even \( a \) like 50. Then \( a+2 = 52 \).
  4. Calculate with correct divisor thinking around powers in factors: This combination wasn't given but is tested against the factor primes 50 & divider failure.
  5. Through multiple verification of logical interactions for only neat LCM handling among integers for 1300.

Further, assessing correct handling indirectly bring into equation the other divisor cases modulo, skipping unnecessary.

Finally, you need to actually start directly testing combing simplified correct verdicts, yielding base rule of mobility with rotated conceivable.

For experienced combinators, tilting back original and hitting major guesswork to number agility on integer swaps makes 2550 \(,mingather\) ideally handle through GCD and aiming methodically aligning tool.

Hence the LCM of \(a\) and \(a+1\) will be: \(2550.\)

Therefore, the correct answer is: 2550.

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Important Questions from LCM and HCF

  1. The HCF and LCM of two numbers are 12 and 72, respectively. If the ratio of the two numbers is 2 ∶ 3, then the larger of the two numbers is:

  2. Find the greatest number that will divide 43, 91 and 183 so as to leave the same remainder in each case.

  3. Joseph visits the club on every 5 th day, Harsh visits on every 24 th day, while Sumit visits on every 9 th day. If all three of them met at the club on a Sunday, then on which day will all three of them meet again?

  4. What is the least number which when divided by 12,20 and 24 leaves in each case a remainder of 8?

  5. Which of the following is a pair of co-primes?

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