You divide the damage as you cast Forked Bolt, not as it resolves. Each target must be assigned at least 1 damage. (In other words, as you cast Forked Bolt, you choose whether to have it deal 2 damage to a single target, or deal 1 damage to each of two targets.)
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.