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When a number is divided by 1,2,3,4,5, ....

When a number is divided by 1,2,3,4,5, .... ,(n-1), n individually it leaves 0,1,2,3,4,.... ,(n-2), (n-1) respective remainders, then this number can be :
(i) `(n!)`
(ii) `(n!-1)`
(iii) [L.C.M. of 1,2,3, ..., n)-1]

A

BOTH (i) AND (ii)

B

BOTH (ii) AND (iii)

C

ONLY (iii)

D

ONLY(ii)

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to determine which of the given options can represent a number that leaves specific remainders when divided by integers from 1 to n. The number must leave remainders of 0, 1, 2, ..., (n-1) when divided by 1, 2, 3, ..., n respectively. ### Step-by-Step Solution: 1. **Understanding the Problem**: We need a number \( x \) such that: - \( x \mod 1 = 0 \) - \( x \mod 2 = 1 \) - \( x \mod 3 = 2 \) - ... - \( x \mod n = n-1 \) This means that \( x + 1 \) must be divisible by all numbers from 1 to n. 2. **Analyzing the Conditions**: From the above conditions, we can deduce that: \[ x + 1 \equiv 0 \mod k \quad \text{for } k = 1, 2, ..., n \] This implies that \( x + 1 \) is a common multiple of all integers from 1 to n. 3. **Finding the Number**: The least common multiple (LCM) of the numbers from 1 to n is denoted as \( \text{lcm}(1, 2, ..., n) \). Therefore, we can express \( x \) as: \[ x = \text{lcm}(1, 2, ..., n) - 1 \] 4. **Evaluating the Options**: Now we will evaluate the given options: - **Option (i)**: \( n! \) - \( n! \) is divisible by all integers from 1 to n, so \( n! \mod k = 0 \) for all \( k \). This does not satisfy our conditions. - **Option (ii)**: \( n! - 1 \) - \( n! - 1 \) will leave a remainder of \( n-1 \) when divided by \( n \), \( n-2 \) when divided by \( n-1 \), and so on, fulfilling the conditions. - **Option (iii)**: \( \text{lcm}(1, 2, ..., n) - 1 \) - This also satisfies the conditions as derived above. 5. **Conclusion**: The correct options that satisfy the conditions are: - (ii) \( n! - 1 \) - (iii) \( \text{lcm}(1, 2, ..., n) - 1 \) ### Final Answer: The number can be: - (ii) \( n! - 1 \) - (iii) \( \text{lcm}(1, 2, ..., n) - 1 \)
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