Question

determinati ultima cifra a numerelor de mai jos: 2015²⁰²¹+2016²⁰²¹+2017²⁰²¹+2018²⁰²¹+2019²⁰²¹
VA ROG URGENT DAU COROANA​

Answer 1

Răspuns:

6

Explicație pas cu pas:

U(2015²⁰²¹) = U(5²⁰²¹) = U(5) = 5

U(2016²⁰²¹) = U(6²⁰²¹) = U(6) = 6

U(2017²⁰²¹) = U(7²⁰²¹) = U((7⁴)⁵⁰⁵×7) = U(7) = 7

U(2018²⁰²¹) = U(8²⁰²¹) = U((8⁴)⁵⁰⁵×8) = U(8) = 8

U(2019²⁰²¹) = U(9²⁰²¹) = U((9²)¹⁰¹⁰×9) = U(9) = 9

=>

U(2015²⁰²¹+2016²⁰²¹+2017²⁰²¹+2018²⁰²¹+2019²⁰²¹) = U(5+6+7+8+9) = U(35) = U(5) = 5