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Math and Logic Problem Solving
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A number when divided by 7 leaves remainder 3 then which of the following is exactly divisible by 49? ("^" means power)
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A
(n-3)^2
💡 Explanation:
If n divided by 7 leaves remainder 3, then n = 7k + 3. Then (n-3) = 7k. Squaring both sides gives (n-3)^2 = (7k)^2 = 49k^2. Since 49k^2 is a multiple of 49, (n-3)^2 is exactly divisible by 49.