Click here for the Problem Extension Worksheet version of the Problems of the Week.
Click here for an MS Word version of the Problems of the Week.
Click here for the Canadian Problem Extension Worksheet version of the Problems of the Week.
Click here for a Canadian MS Word version of the Problems of the Week.

Lower Elementary:
Question: Frankie buys a sandwich that costs $4.55 with a $5.00 bill, 2 quarters, and 1 dime. How much change does she get?
Answer: $1.05
Solution: Since 2 quarters are worth 50¢ and a dime is worth 10¢, Frankie pays for her sandwich with $5.00 + $0.50 + $0.10 = $5.60. So, she gets $5.60 – $4.55 = $1.05 in change.

Upper Elementary:
Question: Emily is baking cookies. She arranges the cookie dough blobs on a baking sheet in 7 rows. Every even numbered row has 7 cookies, and every odd row has 8. How many cookies does Emily bake?
Answer: 53 cookies
Solution: The even rows—the 2nd, 4th, and 6th rows—each have 7 cookies. Three rows of 7 cookies have 7 × 3 = 21 cookies. The odd rows—the 1st, 3rd, 5th, and 7th rows—each have 8 cookies. Four rows of 8 cookies have 8 × 4 = 32 cookies. That makes 21 + 32 = 53 cookies in total.

Middle School:
Question: Billy and Cody have a pizza-eating contest to see who can eat a whole pizza faster. Billy can eat a sixth of a pizza in 21/2 minutes. Cody can eat an eighth of a pizza in 11/2 minutes. By how many seconds does the pizza-eating contest winner win?
Answer: Cody wins by 180 seconds.
Solution: Billy finishes his pizza in 21/2 × 6 = 15 minutes. Cody finishes his pizza in 11/2 × 8 = 12 minutes. That means that Cody finishes the pizza 15 – 12 = 3 minutes faster, and 3 minutes is equal to 3 × 60 = 180 seconds.

Algebra and Up:
Question: The volume of a cone is 1/3 × the area of its base × its height. Allison orders a cone-shaped hand roll from a sushi restaurant that is made of seaweed filled with rice, eel, and avocado. If the hand roll is 2 inches across at its base, its height is 2 inches, and a third of it is filled with eel and avocado, what is the volume of the rice inside the hand roll?
Answer: 4/9π inches cubed
Solution: The base of the cone has a diameter of 2 inches, which means its radius is 1 inch, so its area is πr2 = π. If we plug that value into the formula for the area of a cone, we get 1/3 × π × 2 = 2/3π inches cubed. Since a third of it is filled with eel and avocado, that means two thirds of it is filled with rice. Two thirds of 2/3π is 4/9π inches cubed.