No. A person must choose an exit from the 2 listed.

Either be fried from the sun by the magnifying glass, or be killed by the dragon.

# Challenge Math and Brain Teaser Problems!

**Stradyvarious**#203

**MR.GAM3R**#207

## Answer?

Wait for it to be nighttime. The sun would have set, and the dragon would be sleeping. Ok maybe not the second part

**t1_hopscotch**#208

## I have not looked at @JonnyGamer's answer but the first thing that came to mind was triangle numbers too!

Formula for n-th triangle number = n(n+1)/2

n(n+1)/2 = 210

n(n+1) = 420

nĀ² + n = 420

nĀ² + n - 420 = 0

(n + 21)(n - 20) = 0

[insert school maths explanation processes]

n = 20 years old

sorry that I haven't elaborated further, just wanted to try this quickly

**t1_hopscotch**#209

Wow this is awesome and even more lovely that you explained them ā meanwhile I was too anxious to try out the problem after not being able to get on the forum haha ā You know what, you could collect what you wrote and save it in a blog post!

**JonnyGamer**#210

Yes! I'll do that!

I'd love to work on the blog posts with you over the summer, it's going to be a lot of fun!

**MR.GAM3R**#216

New brain teaser! Difficulty 6/10.

Can you prove that seven is half of twelve?

Remember to put your answers in [spoiler][/spoiler] tags!

**MR.GAM3R**#218

The question is how 7 is *half* of 12. And no, that is not the answer, at least not the one I know.

**JonnyGamer**#220

**t1_hopscotch**#221

Ooh very interesting question!

## Hmm the only thing I could think of...

...was different bases, until I saw you'd put it in words rather than 7 equalling 12

If it were base twelve, 12_{12} would equal fourteen, in which case 7 is indeed half of 14.

I have heard of problems like "when does 11 + 2 = 1" in which case, answer is on a clock but I don't think that works for this one here. This is an interesting problem

And woah @JonnyGamer, your friend's worksheet looks really fun!! So many to choose from... one that caught my eye was the second one under the heading 'Algebra II & Geometry'

**JonnyGamer**#222

Yeah! That one is really fun!

(I actually just solved it today! )

Apparently the trig one is extremely mean