# These 10 questions should take 12 minutes?

Fredrik
Staff Emeritus
Gold Member
It took me about 14 minutes 30 seconds. I'm not fast with these things, but at least I got them all right. I think I got overconfident after doing the first four in less than 4 minutes, and slowed down a bit. I don't think I would make that mistake twice.

I had completed 8 questions when the clock passed 12 minutes.

Are you allowed to use a pen and paper? I did for the equation in question 10. I can do these things without a pen, but then I need more time.

10 correct, 4:45.
Whoa. That's crazy fast.

#5: Can't divide in my head anymore. By this point I was wondering how anyone could do this quiz in 10 minutes. 668 / 4 = 100 with 268 left over. 268 / 4 = 60 with 28 left over. 28? 28 doesn't look divisible by 4. :tongue:
I lost some time on this one too, but after a while I realized that all you have to do to check if something is divisible by 4 is to divide by 2 and see if the result is even or odd.

Last edited:
OmCheeto
Gold Member
...
after a while I realized that all you have to do to check if something is divisible by 4 is to divide by 2 and see if the result is even or odd.
I figured that out after the quiz was over. :grumpy:

All those simple math tricks we knew when we were 10 years old.......

All gone, like the rest of my marbles...... ...
Are you allowed to use a pen and paper?...
Try out several more free tests there, you'll not be able to solve some problems without them.

Some of the companies I took the IQ tests as what they called them used these similar problems which are a bit selectively harder. It took me a long time to solve 10. They evaluated me as an idiot of course.  Matterwave
Gold Member
10 correct, 4:45.

I missed the "A or C = 0" option, that saved some time.

#5 can be solved as "6^5 - 6^4 = 6^4 (6-1) = 6^4 * 5" then you don't have to divide or multiply anything (because the right answer is given as 6^4 as well).
dang, you are supa fast

mfb
Mentor
To test if a number is divisible by 4, you just need the last two digits - 100 is divisible by 4, so is every multiple of it. Therefore, 75654 is divisible by 4 if and only if 54 is.

20/4=5, so we can do the same trick again: At the next to last integer we just have to check if it is even or odd.
If it is even, we can remove it as multiple of 20, and the number is a multiple of 4 if the last digit is 0, 4 or 8.
If it is odd, we can replace it by 1, and the number is a multiple of 4 if the last digit is 2, or 6.

Examples:
647743534 -> 3 is odd, check if 14 is divisible by 4 -> no -> done.
762 -> 6 is even, check if 2 is divisible by 2 -> no -> done

There are tons of those tricks and they really make those tests and also real scientific problems easier.