Can you count the number of tasks

The computer performs $3 \times 10 + 0 = 30 \space tasks$ in $11 \space secs$ i.e. $\lfloor\frac{2018}{11}\rfloor\times 30 + (2018-\lfloor\frac{2018}{11}\rfloor\times 30)\times 3 = 5505 \space tasks$ in $2018 \space secs$ .

We can generalize the situation in this way

After this ,it is just a matter of substituting n=2018 seconds to get 5505 tasks as the answer.

of every 11 seconds one second is not productive (total)/11 rounded down = number of unproductive seconds. therefore total - unproductive = productive seconds. Every productive second 3 tasks are done. Therefore amount of tasks = 3*productive . In the case of this question :

(2018 - floor(2018/11) ) * 3 = (2018 - 183)*3 = 5505