1. Which single digit should be placed in all three of the boxes shown to give a correct calculation?
$\square$
$\square \times$ $\square$ $=176$

A 3
B 4
C 5
D 6
E 8
SolUtion
B

Note first that $33 \times 3250$. However, $44 \times 4=176$ and hence the missing digit is 4 .