The best compatible number for estimating the quotient of 648 ÷ 7 is 630, as it is close to 648 and divides evenly by 7, providing an easy-to-calculate estimate.
The question is asking for the best compatible number for estimating the quotient when dividing 648 by 7. A compatible number is a number that is close to the original number and divides evenly by the divisor, making it easier to compute an estimate mentally.
In this case, 700 is not a good choice because it is significantly higher than 648 and does not divide evenly by 7. Meanwhile, 670 is also not ideal as it does not divide evenly by 7 either. Option (d) 640 is very close to 648 but does not give a whole number when divided by 7. The best option is (b) 630 because it is close to 648 and it divides evenly by 7 (since 7 x 90 = 630), giving us the compatible quotient of 90.
Therefore, the best compatible number for estimating the quotient of 648 ÷ 7 is option (b) 630.