Estimate the sum $$(42505+27807+21397)$$ to the nearest thousand.
$$42505$$ estimated to the nearest thousand $$= 43000$$
$$27807$$ estimated to the nearest thousand $$= 28000$$
$$21397$$ estimated to the nearest thousand $$= 21000$$
Now, the sum of the estimated numbers is $$43000+28000+21000=92000$$
Hence, the sum is $$92000$$.