A student has 3 bags of marbles, with 7 marbles in each bag. How many marbles in total?

• A. 27
• B. 17
• C. 21
• D. 24

Answer: (C)

Think of having several equal groups. The total is found by multiplying how many groups there are by how many items are in each group. Here there are 3 bags with 7 marbles in each, so 3 × 7 = 21. You can also add 7 + 7 + 7 to see the same result, which is 21.

27 would mean a different setup (like 3 bags of 9), 24 would be three bags of 8, and 17 isn’t consistent with three groups of seven, so those don’t fit the given situation. The total marbles are 21.