The minute hand of a watch is 42 mm long. Taking π as 3.14, the area (in mm2) swept by it in 30 minutes…

The area swept is about 2769.5 mm². In 30 minutes the minute hand turns through half a circle, so it sweeps $\frac{1}{2}\pi r^{2}$ $= \frac{1}{2} \times 3.14 \times 42^{2}$ $= \frac{1}{2} \times 3.14 \times 1764$ $\approx 2769.5$ mm². $44\pi$ (about 138) and 728 are far too small, and $1040\pi$ (about 3266) is larger than the half-circle area.