Narcissa shrugged, uncertain where her friend was going with this. "Those are the constants, and some Arithmancer long ago decided to name them Clotho, Lachesis, and Atropos. Clotho works on the variables overall to begin working the equation, Lachesis solves the length of time it takes, and Atropos gives you the final answer. But as you see here, Clotho's value that you're supposed to use in this type of equation just doesn't work, and it destabilizes the entire arithmantic formula."