To three significant figures, the measurement 1246 g should be reported as [number] g.

1250 g

Explanation:

The measurement 1246g shows four figures. To show this measurement to three signficant figures you must change the last digit to 0 and round properly.

To report the measurement 1246g to three significant figures you must replace the last digit (the 6) with 0 and round the previous one (the 4) to the closest integer: 1250 is closest to 1246 than 1240, so the correct rounding is 1250.

In an integer number, the zeros after the last none zero digit are not sginificant figures; that is why the zero in 1250 g is not significant and this number has just three significant figures.