In the Red Box starter game, when you choose to be a Rogue, it says that your damage is 1d4+4. When I rolled the dice, it had all three "4" symbols facing up. Did I do 4 damage, or do I add them up to 12?
There are two different styles of pyramid-shaped d4 dice:
The purple d4 on the left is read by having the number at the bottom be the result of the roll (in this case, a 1). The light blue d4 on the right is read by having the number at the point be the result of the roll (in this case, a 4).
In both die types, the result is the number that is right side up, and it will be in the same position no matter which side of the die you are looking at. You don't add the numbers from different sides together (they will always be the same), you just look at one side and look at the number that is supposed to indicate the result.
For your specific case of 1d4+4, you would roll a single d4, look for the result on one of the die faces (just one side, don't factor in the other sides; they're the same), and then add 4 to the result. So the left die shown above would be 1+4=5 and the right die shown above would be 4+4=8.
A four sided die is a tetrahedron, so it lands with a vertex pointing up, not with a face pointing up. The problem is that you cannot paint a number on a vertex, only on a face, right? So there are two solutions.
You can treat the upward-facing vertex as the outcome of the roll, and label it by printing a number close to the vertex. That works, but not all players can see it. So the number is replicated on all faces which are adjacent to the vertex.
Alternatively, you can treat the bottom face as the outcome of the roll and label that by placing a number close to the edge of that face. Again, you have to replicate this on three faces so everyone can see.
In table top games such as board games and card games, everyone should see and easily read the shared state, like the roll of a die, without any objects having to be manipulated (turned around). If objects have to be lifted and turned around, that creates opportunities for cheating or accusations of cheating that spoil the game. This is probably why six sided dice do not use numerals, but symmetric patterns of dots. Also note how the ranks and suits on playing cards usually appear twice with 180 degree symmetry.
So three 4's are coming up because the die has four corners, each of which adjoin to three faces. One of them is labeled 1, 1, 1. Another one 2, 2, 2. And then two more are 3, 3, 3 and 4, 4, 4. You do not count these numbers three times.
A nice feature of these tetrahedral dice is that the number that has come up is always upright on all four faces, so you can just ignore the digits that aren't upright. By following that rule, you can read either type instantly.
I was taught two methods (way back in the 80's when I started out). One is the number on the bottom of the face (which will the same on all three showing faces) or you can pick it up and look at the bottom face and the result is the number NOT listed.
In all cases the number would be the same. :)
Early 4-siders had the die number printed on the bottom of the triangle (it took me several years to understand this, before then I picked up the die, looked at the 3 numbers on the bottom and counted the missing one as the roll!). Modern ones have them printed on the apex.