why zero look like this 0 ?

Question

who choose that? and why people accept that?

Answer 1

At one point, written numbers (single digits) had a shape such that the value they represented was equal to the number of acute angles they contained.

1 was a vertical bar with a tail connected at the top, going towards the left (and downward) -- one angle.

2 was like a modern Z (two angles)

3 was like a W with the open ends of the V's pointing left. 2 angles at the bottom of the V's plus a third angle where the V's join.

etc.

7 was vertical bar, with a "tail" going left at the top (1 angle), a horizontal bar crossing at the middle (4 angles) and another horizontal bar at the bottom, like a serif (2 angles). Total = 7 angles.
That is why wome people still write their 7's with a tiny bar crossing in the middle.

When the time came to find a representation for a zero, the two "natural" choices were a dot (like a decimal point but raised from the line) or a circle. Both of them have no angles (i.e., "zero" angle).

The zero was harder to miss than the dot (and the dot is used for so many other purposes in math).

Answer 2

Why the circular shape? It's a simple shape that looks like an empty hole or void, perfect for denoting zero quantity of something.

Why do people accept it? We need common standards if we are to communicate effectively, so there is no reason to change it.