King Roo has a set of four six-sided dice. If they're placed next to each other, they form all manner of four-digit numbers, as seen below.
One day, after a long Dice-A-Roo session in the afternoon, he decided to take a break and find all the possible four-digit combinations these dice could form, including those with the six turned upsidown because, well, he's King so he can do what he wants.
After a bit of work, he found all the combinations, and then decided to take one more step...
If King Roo added up all the possible combinations formed by these four dice, what would the sum be?
Please enter just the number with no punctuation or formatting. (For example, 1,999 should be entered as 1999.)