Convert 6 days into minutes and express the answer in standard form.

There are 24 hours in 1 day.

$$6 \text{ days} \times 24 \frac{\text{hours}}{\text{day}} = 144 \text{ hours}$$

There are 60 minutes in 1 hour.

$$144 \text{ hours} \times 60 \frac{\text{minutes}}{\text{hour}} = 8640 \text{ minutes}$$

Standard form requires the number to be written as $a \times 10^n$, where $1 \le |a| < 10$.
To convert 8640 to standard form, move the decimal point to the left until there is only one non-zero digit before it.

$$8640 = 8.640 \times 10^3$$

The final answer is $\text{8.640} \times 10^3 \text{ minutes}$.