Skip to main content

2024 AMC 10B Problem 7

Problem 7 of 25EasierAlgebraNumber TheoryArithmetic

What is the remainder when 72024+72025+720267^{2024} + 7^{2025} + 7^{2026} is divided by 19?19?

Answer choices

Show solution

Solution

Pull out the common power: 72024+72025+720267^{2024} + 7^{2025} + 7^{2026} =72024(1+7+49)= 7^{2024}(1 + 7 + 49) =72024⋅57.= 7^{2024} \cdot 57. And 57=3⋅19,57 = 3 \cdot 19, so the product is a multiple of 19.19. The remainder is 0.0. Thus, A is the correct answer.
AoPS wiki

Tagged: modular arithmetic · factoring · exponent

More practice