If I roll an odd number, next Thursday is going to be a VERY annoying day (for me, Thursdays always are more annoying than normal, I don't know why) EvenNumberPlease = 9

the minimum with 20 dices is 20, the maximum is 400, so, there are 380 possibilities of numbers, it means each of these has about 0.26% chance of rolling 400, by that way, we would have to roll 20d20 263 times to have 50% chance of rolling at least one 20d20=400