Post's inversion formula

Post's inversion formula lets you figure out the equation of something if you know the answer. Imagine you have a box of chocolates. You know that if you have 3 chocolates, there will be 6. The equation for this is "3 chocolates = 6 chocolates". Post's inversion formula helps you figure out the equation if you know the answer but not the equation. So, if someone gave you 6 chocolates and you wanted to know how many chocolates you started with, you could use Post's inversion formula to figure it out. The equation for this would be "6 chocolates = 3 chocolates".