CEMC Pascal, 2022

On a number line, $-3.4$ is
between $-4$ and $-3$.

This means that $-3.4$ is closer to
$-4$ and $-3$ than to any of 0, 3 or 4, and so the
answer must be $-4$ or $-3$.

If we start at $-3$ and move in the
negative direction (that is, to the left), we reach $-3.4$ after moving $0.4$ units.

It then takes an additional 0.6 units to move in the negative direction
from $-3.4$ to $-4$.

Therefore, $-3.4$ is closer to $-3$ than to $-4$, and so the answer is (B) or $-3$.

Alternatively, when comparing $-3$,
$-4$ and $-3.4$, we could note that $-3.4$ is between $-3.5$ and $-3$ and so is closer to $-3$: