How to measure the center of a round coin

According to your needs and tools, it should be easy to find three or four methods, right?

1. Hold the coin with two right triangles and a ruler, and read the diameter of the coin from the ruler. The intersection of any two diameters is the center of the circle.

2. Cover the coin with a blank sheet of paper, and write it lightly with a pencil, so as to leave the mark of the coin on the paper (it must be a circle), and then take any three points on the circle to form a triangle, and the ruler and compass can find out the center of the circle.

3. You can know the circumference of this coin and the diameter of this coin after winding the wire once.

4. Diameter of oil gauge caliper.