Mr. Kooiker's 4th Grade Blog

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Math Challenge Answers

So, you decided to take the “next step” math challenge. Way to go! The problems were not easy…

Seth had some marbles that he shared equally with Josh. Then Josh gave half of his marbles to his sister, Elaine. If Elaine received 4 marbles, how many marbles did Seth start with?

Seth started with 16 marbles.


A museum holds two crafts days for children. They have enough supplies for 138 projects. On Saturday, 72 children make projects. On Sunday, 57 children make projects. If each child makes one project, does the museum have enough supplies for all the children? Explain how you can use estimation to answer the question.

Yes, the museum has enough supplies for all the children. I know this because I rounded 72 to 70 and 57 to 60. Since 70 is an underestimate and 60 is an overestimate, it should be reasonable. Then, I used mental math to add 70 + 60 = 130.


Jenny has $155. She buys 4 framed pictures for $22 each. Then, she buys a book for $18. How much money does Jenny have left?

Jenny has $49 left.

How did you do? Check back later for more math challenges! 🙂

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