What's the meaning of 0-9 digital axisymmetric figure? 3Q

What's the meaning of 0-9 digital axisymmetric figure? 3Q

How many numbers are there: 0, 1, 3, 8? Can you help me explain? Answer: fold along a straight line, the two sides of the line can overlap. Ask: can you give me an example not to kiss? Answer: 8, fold it horizontally, the two circles can overlap! Add: how many years is the kiss? Ask: Grade 1, now primary school students are really difficult to learn. Answer: no wonder, I'm a supplement to the second