2
$\begingroup$

$12 = 0$
$1234 = 1$
$123456 = 2$
$12345678 = 4$

$369 = 2$
$248 = 3$

$2 = 0$
$3 = 0$
$5 = 0$
$7 = 0$
$11 = 0$
$13 = 0$

What does:
$123456789 = ?$
Why?

Hopefully isn't too hard, please ask if you need any test cases.

$\endgroup$
  • 1
    $\begingroup$ Wow this was way too easy. Really should amp up the difficulty level $\endgroup$ – qwertylpc Jul 16 '15 at 16:05
3
$\begingroup$

The answer is:

5

because

You're counting the number of holes in the numbers.

$\endgroup$
  • $\begingroup$ @JLee Thanks. I didn't know how to do the hide thingy. $\endgroup$ – Gummy bears Jul 16 '15 at 16:08

Not the answer you're looking for? Browse other questions tagged or ask your own question.