I am writing a program in a version of Basic for showing the orbits of 3 bodies. To check that it works I do the following. Each body is of the same mass say 50. I cannot get them to rotate in three separate orbits of equal size, which is the test that the program works. I place the bodies at the respective corners of an equilateral triangle so that the three bodies are an equal distance apart. The coordinates of the three bodies are: x1,y1 = (-500,-288.675...), x2,y2 = (500,-288.675...), x3,y3 = (0,577.35...), and their velocity components are: Vx1,Vy1 = (20,-34.6...), Vx2,Vy2 = (20,34.6...), Vx3,Vy3 = (-40,0). This way the change of momentum of the entire system equals zero. The result that I get is that body-2's orbit coalesces with body-3's and three's coalesces with body-1's e.t.c., to give three bodies having the same large anticlockwise orbit, instead of three separate orbits. I know that the starting positions and directions of the initial velocity components are critical.While I have the initial positions correct I do not know if the directions ' are correct. If I put any two bodies in a clockwise orbit and the remaining body in a anticlockwise orbit, I seem not able to fulfill the requirement that the change in momentum of the entire system equals zero, yet I feel that this is required to get the system of masses orbiting correctly. Help would be appreciated. Note : In order for these magnitude of figures to give orbits at all I have set G=1.