MathDB

1

Part of 2006 CentroAmerican

Problems(1)

Find the last digit of a sum

Source: Central American Olympiad 2006, Problem 1

4/30/2007
For 0≤d≤90 \leq d \leq 9, we define the numbers Sd=1+d+d2+⋯+d2006S_{d}=1+d+d^{2}+\cdots+d^{2006}Find the last digit of the number S0+S1+⋯+S9.S_{0}+S_{1}+\cdots+S_{9}.
modular arithmeticgeometry3D geometry