Question

Which of the following numbers will completely divide $(4^{61}+4^{62}+4^{63}+4^{64})$?

• A. $3$
• B. $10$
• C. $11$
• D. $13$

Answer 1

The correct option is B $10$

$(4^{61}+4^{62}+4^{63}+4^{64})=4^{61}\times (1+4+4^2+4^3)=4^{61}\times 85$
$=(4^{60}\times 340)$, which is divisible by $10$.