Yeah i check all of them. When if fiddle around i can get a rudimenttary simulation (planets orbit eachother) but it isnt accurate to the equation F = G M1M2/r2. Rather, i just do Gravitational constant * mass1 * mass2, which works, but really inacurate. Gravity slingshots dont work, orbhits are really wonky, all planets eventualy come into the sun etc. Perhaps there is an error in the calculation i put?