# Holiday Math Puzzle

As we begin to have a few weeks away from our classrooms, let's try a few math puzzles:

Directions: One number in each group does not belong, what is the number, and explain why it doesn't belong.

1. 12, 29, 24, 37, 2, 83
2. 42, 26, 9, 12, 15, 27
3. 25, 16, 49, 81, 36, 54

If we get these solved and you have another math puzzle to share then post it.  Let's develop our mathematical thinking and support each other.

Brooke ### WODB :)

Which One Doesn't Belong???  I wonder how hard students who aren't awash in arithmetic for years would find these.  Would it be frustrating?  Or would they enjoy the process? ### Multiple Solutions?

At a quick glance I'm seeing:

Group 1: The 2 doesn't belong because it's a one digit number

Group 2: The 26 doesn't belong because it's not divisible by 3.

Group 3: The 54 doesn't belong because it's not a perfect square.

But if this works like WODB then I'm interested in other observations.... ### wodb

1.     83 doesn't belong because it is the only number greater than 50.

2.     9 doesn't belong because it is the only single digit number.

3.     81 doesn't belong because it is the only number without a 4, 5, or 6 digit. ### New Puzzle

Here is a problem I recently gave to my math students.  Only 2 students got it correct.  Think carefully before you answer.

A boat is in a bay and has a ladder hanging off the side.  There currently 4 rungs showing.  Each rung is 12 inches apart.  The water in the bay is rising 6 inches every hour.  After 3 hours how many rungs are still showing? ### I love it

In reply to by Miss Christine

Thanks for the new puzzle, I need some time to think about this...then I will post my response.  I hope others will jump on and post, their responses and other puzzles.  Sometimes practitioners need to flex their brain muscles and we are a very supportive group to do that in. ### New Puzzle

Here is a problem I recently gave to my math students.  Only 2 students got it correct.  Think carefully before you answer.

A boat is in a bay and has a ladder hanging off the side.  There currently 4 rungs showing.  Each rung is 12 inches apart.  The water in the bay is rising 6 inches every hour.  After 3 hours how many rungs are still showing? ### A third way....

1.  83 doesn't belong, because it's the only number where the tens digit is larger than the ones digit

2. 42 doesn't belong, because it's the only number where the ones digit is smaller than the tens digit

3. 81 doesn't belong, because if you put the numbers in order least to greatest, it's the only one that isn't a consecutive number (doesn't follow a number with a tens digit one less than it) ### Mathigon Puzzle Calendar

Hi all,

Mathigon is hosting a December puzzle calendar starting tomorrow: https://mathigon.org/puzzles#2021

Here's a sample puzzle from a few year's ago:

Rearrange these numbers and symbols to make a true equation:

2 3 4 5 + =

Enjoy.

Eric