Did you learn some physics in grade three? We use physical thinking to solve problems (whole plus isolation) and use geographical terms "revolution" and "rotation":
First, study the "revolution" of sports currency. If the center of the moving coin is isolated, then the locus of this point is a great circle, the radius r of this great circle is twice that of the coin (if you still don't understand it, you can operate it yourself), and two coins can be regarded as a whole (particle), then the distance of the moving coin can be regarded as the movement of the center of the circle, and the length of the distance is L, and L can be represented by R.
Then study the "rotation" of a moving coin (the coin can't be regarded as a particle at this time). The movement distance of any point outside the coin is equal to the circumference l of the coin. After calculation, L=2l.
Therefore, if the angular velocity of the coin "revolution" and "rotation" are the same, it is 2 turns. (For example, it must be 1 circle after "revolution" for half a circle. )
If there is a problem, try to understand it comprehensively, which will be faster and deeper, provided that other subjects are better. ...