Number trouble in here

Question

I have been given 24 hours to solve this.

So, my friend has given me 10 examples.

$$1024 = 1$$

$$1000 = 3$$

$$2880 = 5$$

$$6591 = 2$$

$$2113 = 0$$

$$1345 = 0$$

$$1987 = 3$$

$$8888 = 8$$

$$5632 = 1$$

$$6124 = 1$$

So, the question is

$$ 2456=?$$

Answer 1

The answer is:

1

Reason:

the result is the number of round holes in the digits.

0 - one hole, 1 - zero holes, 2 - zero holes, 3 - zero holes, 4 - zero, 5 - zero, 6 - one hole, 7 - zero, 8 - two holes, 9 - one hole.