First of all, 123 attack gets to 184 with a +1 modifier, not +2.

Secondly, note: the stat would become 184. Pokemon uses what is called

**integer division** in mathematics. You can read more about integer division

here. It uses integer division for

every calculation, basically.

In reality, Pokemon does not multiply by decimals, either. For example, in the example for the +1 stat modifier above, the game doesn't really multiply by 1.5. What it really does is multiply by 3, and then "integer divide" by 2. (That's why I wrote 3/2 next to the modifier). We prefer to multiply by 1.5 and then "round down" (technically, use the

floor function) the answer because it's easier that way, for us humans.

Also, it does make a lot of difference. Just ask those people who would love to outspeed certain things. A difference of 1 in speed can make a hell of a lot of difference. That's why Speed IVs are arguably the most important ones to get 31 in.