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MathsHardNumerical2021 · 22 Jul Shift 1

Q82.The sum of all the elements in the set {n ∈{1, 2, … … , 100} ∣ H.C.F. of n and 2040 is 1} is equal to __________.

What This Question Tests

This question requires finding the sum of integers co-prime to a given number within a range, involving prime factorization, GCD concept, and the Inclusion-Exclusion Principle for efficient counting.

Concepts Tested

Greatest Common Divisor (GCD)Inclusion-Exclusion PrincipleSum of arithmetic seriesPrime factorization

Formulas Used

Sum of first N natural numbers = N(N+1)/2

Inclusion-Exclusion Principle

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