Final answer:
In this case, he could purchase 49 gumballs, which would allow each friend to receive 7 gumballs and leaves no leftovers.
Step-by-step explanation:
The subject of this problem is mathematics, specifically division and multiples. Bobby wants to buy gumballs for his 7 friends in such a manner that he is left with no extras. To figure out the maximum number of gumballs he can purchase, he should use approach D: Make a list of the multiples of 7 and then purchase the highest multiple of 7 that is less than 51. In this case, the highest multiple of 7 less than 51 is 49 (7*7=49). This way, each friend gets 7 (49/7=7) gumballs and no gumballs will be left over.
Bobby could also use approach A: Divide 51 by 7 but that will give him a remainder (remainder is 2), which means he will be left with some gumballs. Approaches B and C are also valid but approach D provides the most straightforward answer.Therefore, the best approach would be to use multiples of 7 and purchase 49 gumballs so that each friend gets 7 gumballs and there are no leftovers.
Learn more about Division and Multiples