Hi everybody!
This is Jason again from Collaborative Mathematics.
This is Challenge Video number 2.
Thanks, first of all, to everybody who has participated so far.
Thanks to all of the Twitter-followers, and Facebook-likers,
and YouTube-subscribers that we’ve gotten.
Thanks to the three people who uploaded video responses to Challenge Video
number 1, so far. That was really cool.
And thanks also to people who have done the problem and haven’t uploaded
videos.
I’ve heard from people who have just done
it at their desks, individually.
And some teachers who have done the challenge with groups of students.
All of that is really fantastic and I appreciate
everybody’s participation.
I hope to see some more participation with
Challenge number 2. Here it is!
I’ve got my calculator here.
Notice that when I take the number 1089
and I multiply by 9
I get 9801.
"Who cares?" you say.
But check it out!
That’s the same number, it’s just been flipped.
1-0-8-9 becomes 9-8-0-1.
That’s cool.
And it doesn’t happen, generally speaking, right?
If I picked another four-digit number and I multiply by 9,
like if I took 2658 times 9, I get something else.
It doesn’t flip around.
So something interesting is happening in the first case
that is not happening in the second case.
So let’s name that.
Let’s say that the number 1089 is "flipped when multiplied by 9".
Then, the core challenge for this video is:
Which four-digit numbers are flipped when multiplied by 4?
So that’s the core challenge, but of course,
that question might make you wonder about other things, too.
Is 1089 the only four-digit number that is flipped when multiplied by 9?
Are there any 3-digit numbers that are flipped when multiplied by 9?
Or 5-digit numbers that are flipped when multiplied by 9?
Or when multiplied by 4?
What happens when you multiply by 3?
Can you get a number that is flipped when multiplied by 3?
Or by 7?
Or by 13?
There’s lots to be curious about in this area,
so I say explore whatever you find interesting and then upload a response
video with your observations, and discoveries, and any other questions
that come to mind!
Check us out online. We’re at
Collaborative Mathematics . org
There can find little social media buttons that will connect you to our pages on
Facebook, and Google Plus, and Twitter, and YouTube.
So that you can follow, and like, and subscribe to what we’re doing here at
Collaborative Mathematics.
Help us spread the word please, too. Tell your friends!
And go out there and do some fun mathematics!
I look forward to seeing what happens next!