Question

Делится ли 7^2017 + 7^2018 + 7^2019 на 19?

Answer 1

7^2017 + 7^2018 + 7^2019 = 7^2017(7^2 + 7 + 1) = 7^2017(49 + 1 + 7) = 7^2017*57, 57:19 = 3