Lower Elementary
Question: Marshall, Nick, Jaclyn, and Christine each have a piggy bank. Each piggy bank has 99 cents. How many cents do they have in altogether?
Answer: 396 cents
Solution: Add 99 + 99 + 99 + 99. Since 99 is 1 away from 100, we can add 100 + 100 + 100 + 100 and then subtract 4. 400 – 4 = 396.
Upper Elementary
Question: Candice baked 91 cookies. She is making bags with 7 cookies in each to give to her friends. She gave away 5 bags. How many bags does Candice have left?
Answer: 8 bags
Solution: To find the number of bags she made, divide the 91 cookies Into 7 equal groups. 91 / 7 = 13 bags. She gave away 5, so subtract 5 to see how many she has left. 13 – 5 = 8 bags.
Middle School
Question: Drew is 67 inches tall. Harvey is 4 feet and 11 inches tall. How much taller is Drew than Harvey?
Answer: 8 inches
Solution: The Law of Sameness says we can only add and subtract things with the same name. Let’s convert 4 feet and 11 inches into inches. There are 12 inches in 1 foot, so there are 48 inches in 4 feet. Add 11 inches to 48 inches to find Harvey’s height in inches. 11 + 48 = 59 inches. Now subtract the heights. 67 inches – 59 inches = 8 inches.
Algebra and Up
Question: A bag of marbles contains 5 red marbles, 3 green marbles, and 2 blue marbles. What is the probability of drawing a red marble, putting it back, and then drawing a blue one?
Answer: 1/10
Solution: There are a total of 10 marbles in the bag. The probability of drawing a red marble is 5/10, or 1/2. The marble is put back, so there are still 10 marbles in the bag. The probability of drawing a blue one is 2/10, or 1/5. To find the total probability, multiply the two probabilities together. 1/2 x 1/5 = 1/10.
