Math Challenge Archive

Read the answer to the Fibonacci rabbits problem here.

Penguin Challenge: If penguins are taking a nap, and most lie with their white bellies up but every 3rd penguin starting with the 3rd has its black back facing up, what number penguin is the 11th one with its belly up? Answer: The 16th penguin will be the 11th "belly up" penguin.

Note: In real life, penguins do not actually lie belly up.

Rocket Science: If the rocket that brought the Apollo had flown twice as far the 1st day as the 2nd day, which was twice as far as the distance flown on the 3rd day, which was twice as far as the 4th day, how much of the 240,000 miles did it fly on the 1st day?

128,000 miles. With those ratios of distances, on the 1st 3 days Apollo flew 8 times the final day distance, then 4 times that distance, then 2 times that distance, respectively. So the whole trip distance was 15 times the final day’s trip. That gives us 16,000 miles on the final day. Then you just multiply by 2, 4 and 8 to get 32,000 for the 3rd day, 64,000 the 2nd day and 128,000 the 1st day. To double-check, those four numbers do add up to 240,000!

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Last Week's Challenge Problem Answers

1. a) Divide 30 by ½ and add 10. What’s the answer? 70

2. b) Your sock drawer only contains 18 white socks and 18 blue socks. How many times do you need to reach inside the drawer and take out a sock to guarantee a matching pair? 3

3. c) What makes this number unique: 8,549,176,320? The digits are in alphabetical order.

There are 20 nines between 1 and 100. There are 15 squares.

Can you solve this? A fraction becomes 2/3 when 1 is added to both its numerator and denominator and it becomes 1/2 when 1 is subtracted from both the numerator and denominator.

Find the fraction. Answer: 3/5

Answers: Two Truths and a Lie - #2 is a lie. Change 3 3/5 to 3 6/10 and 2 1/2 to 2 5/10, then add them together. 5 8/10 simplifies to 5 4/5, which is larger than 5 1/4. Mashupmath Challenge: Since a bat plus a bat equals 8, then each bat must equal 4. A pumpkin minus a bat (4) equals 1, so the pumpkin must equal 5 because 5 - 4 = 1. Now you can figure out how much the skull is worth 4 + 5 = 9). To figure out how much an owl is worth, divide the sum (9) by 3! You'll find that the owl = 3.