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What is the least number, which when divided by 12, 21 and 35, leaves the same remainder 6.
Question

What is the least number, which when divided by 12, 21 and 35, leaves the same remainder 6.

A.

420

B.

576

C.

414

D.

426

Correct option is D

Given:
We need to find the least number that, when divided by 12, 21, and 35, leaves the same remainder.
The remainder is given as 6.
Concept Used:
This problem involves finding the least common multiple (LCM) of 12, 21, and 35, and using that LCM to determine the required number.
If a number leaves the same remainder when divided by multiple divisors, the required number can be found using the formula:
Required number = (LCM of divisors) × n + remainder,
where n is a positive integer.
Solution:
Finding the LCM of 12, 21, and 35:
Prime factorization of 12: 12 = 2² × 3
Prime factorization of 21: 21 = 3 × 7
Prime factorization of 35: 35 = 5 × 7
To find the LCM, take the highest powers of all the prime factors. So, the LCM is: LCM = 2² × 3 × 5 × 7 = 420.
The required number should be of the form:
420 × n + 6.
For the least number, take n = 1: Required number = 420 × 1 + 67 = 420 + 6 = 426.
However, this number (487) exceeds 420. To adjust the number so that it leaves a remainder of 67 when divided by 12, 21, and 35, we subtract the LCM (420) from 426: 426 - 420 = 6.
Thus, the least number that satisfies the condition is 426.
Final Answer: (d) 426

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