Estimate the product $$758\times 6784$$ using the general rule.
According to the general rule we round off each factor to its greatest place, then multiply the rounded off factors
$$758$$ rounded off to nearest hundreds is $$800$$ as it has $$5$$ in its tens place.
And $$6784$$ rounded off to nearest thousands is $$7000$$ as it has $$7$$ in hundreds place.
$$\therefore$$ Product $$= 800 \times 7000$$
$$= 5600000$$
$$\textbf{Hence, the estimated product is 800}\ \bf{\times}\ \textbf{7000 = 5600000}$$