According to general rule, Round off each factor to its greatest place, then multiply the rounded off factors.

Rounding off 758 using the general rule, as its greatest place is 100’s, therefore we will round off it to nearest hundreds = 800

Rounding off 6784 using the general rule, as its greatest place is 1000’s, therefore we will round off it to nearest thousands = 7000

800 × 7000 = 560000