What is wrong with this picture?
I'm not exactly sure what you mean by "wrong." Anyways, I took a wild guess, and tried to answer the question anyways. To me, it looks like there are some overlapping shapes, and adding a shape on top of another one inverts the colours below. So if you start with a black horizontal rectangle, then place a vertical rectangle on top of it to make a "+" sign, the intersection in the center would turn white. In your picture, one shape seems to be like a big backslash, so in the attached picture, the first image is the original, and the second is what happens if you remove that backslash. The next piece is a smaller vertical rectangle in the top-right corner, and the third figure is the result of removing that. I'm think that what's "wrong" with the picture is that you're not left with a "nice" looking shape.
Well, actually, the remaining shapes look like two circles with a "bow tie" between them. Instead of seeing it this way, you can see the top circle and the left half of the bow tie together as one tear-drop-like object, and take the bottom circle and right half of the bow tie to get another tear drop, so together the two drops make something like a yin-yang symbol. If you treat a tear drop as a single shape, and remove it (say you remove the top), then what you're left with is just the two inner "triangles" of the bow tie coloured black. That's nicer than what was there before.
On the other hand, this could have nothing to do with the problem, since you either haven't said what the problem is, or part of the problem itself is figuring out what you mean by, "what's wrong with this picture."
Interesting. But that isn't it. The coloring of the regions is a dead-end.
I hope I'm not giving too much away: the middle line (the left side of your top-right rectangle) actually extends all the way to the bottom of the figure. And before anyone else mentions it, the picture is not necessarily intended to be symmetrical.
Two tangents passing through the same point on the circle
That's not a problem with the picture, it's a problem with your assumption that the lines are tangent lines and/or that they pass through the same point.
I may have made this too hard. Here is the picture with one flaw corrected:
In the improved version, it seems the number 5 is missing.
I had seen this in the original, but as you say, it had been too difficult. This way it is too easy. The answer is every digit is represented except 2. However this answer does involve the coloring since part of the 4 is obscured by it.
The 2 is there. Take the right half of the top circle, plus the top-left quarter of the bottom circle, plus the horizontal line that cuts the bottom circle in half. Althought it doesn't appear that way because of the colouring, extend that horizontal line all the way to the right of the bottom circle, just as he said the vertical line in the center extends all the way down to the bottom of the bottom circle.
There were 2 things wrong with it. The other thing is, it wasn't underlined. Here is the complete exposition:
Congratulations AKG and jimmysnyder.
It is unusual that the 4 does seem to be more obscured than, say, the 5, even though you have to assume lines are continued for both of them. The inside triangle's right angle seems to lead the eye off to the side, preventing it from automatically completing the vertical.
can any one please explain what does number means ?
That's kind of cool. I like that one. I didn't get it because I thought it was an overlapping issue as was first discussed and when I checked the other answers and say it had to do with numbers I felt dupped. Oh well.
"Number" is a concept we use to quantify things. 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 are all numbers that make up other numbers. Mathematically Pi (the symbol) along with many other symbols could also be considered numbers in that sense.
Separate names with a comma.