>>12793792You can't get 50 from the base damage. Since Pokemon rounds really dumb, you can only get 49 and 51 damage before SE when the random range kicks in, which means you can only get 98 and 102 damage, but not 100. A weak 4x effective move, however, CAN land on 25 damage, which 4x does 100 damage.
If it wasn't for Pokemon's retarded rounding rules, we wouldn't be able to determine this.