### Instruction: Evaluate $\left\lceil\sqrt{140}\right\rceil$.### Response: I know that $\left\lceil x\right\rceil$ means the smallest integer that is greater than or equal to $x$.
So, I want to find the smallest integer that is greater than or equal to $\sqrt{140}$.
I can try to estimate $\sqrt{140}$ by squaring some integers.
I know that $12^2 = 144$ and $11^2 = 121$, so $\sqrt{140}$ must be between $11$ and $12$.
That means the smallest integer that is greater than or equal to $\sqrt{140}$ is $12$.
Therefore, $\left\lceil\sqrt{140}\right\rceil = 12$.