If $8210=8.21 \times 10^{\square}$, then the value that should go in the $\square$ is
(A) 1
(B) 2
(C) 3
(D) 4
(E) 5
$8210=8.21 \times 1000$ so we must have $10^{\square}=1000$ so the required number is 3 .

ANswer: (C)