3. Calculate $$\sqrt{12 \cdot 20 \cdot 60}$$.

Let's calculate this step-by-step:

1. We need to calculate $$\sqrt{12 \times 20 \times 60}$$.
2. First, multiply the numbers inside the square root: $$12 \times 20 = 240$$.
3. Then, multiply $$240 \times 60$$: $$240 \times 60 = 14400$$.
4. So, we need to find $$\sqrt{14400}$$.
5. We know that $$144 = 12^2$$ and $$100 = 10^2$$.
6. Therefore, $$14400 = 144 \times 100 = 12^2 \times 10^2 = (12 \times 10)^2 = 120^2$$.
7. The square root of $$14400$$ is $$120$$.

Ответ: 120