Maplestory "High Five" Private Showcase

Isn't the max level for enhancement skills 50 and not 40? (wondering how many cores they need for last 10 levels)

Yep, the max level for Enhancement skills is 50. But the max rank of a Core is only 25. So you need at least 2 Cores to max out an Enhancement skill! (probably more since its easier to get up to 3-4 lower level ones than 2 level 25 ones)