How do I determine the amount of valence electrons for groups ...

[plus1]

I get that groups 1-2 and 13-18 have valence electrons of 1-8 and I can determine the energy level as well as sublevels s, p, d and f and write the configurations, but what hasn't been explained to me in my book properly is a way of finding out the number of valence electrons of groups 3-12 by just using the periodic table without having to look up each element online. So please tell me what I need to do.

[mydiamond]

It's easy, the number of valence electrons in groups 13 to 18 is the group number minus 10 eg elements in group 13 have 13 - 10 = 3 valence electrons, group 17 have 17 - 10 = 7 valence electrons.

[asan beg]

1..2..3...4...5...6 ...7...8...9...10.. 11...12...13...14.. ..15...16..17...18 ..Group No
1..2..2...2,..2,..2,..2,..2,..2,...2....2,....2.....3.....4.....5.....6....7.....8 ..e in level n
.......1....2...3.. .4...5...6...7....8 ....9...10,...10...10...10...10..10....10..e in level n-1
1..2..3...4...5...6 ...7...8...9...10.. .11..12....13...14. ..15...16..17....18 ..Total e in last 2 levels

I do not know whether this will help.

It depends on what is meant by "valence electrons". Just the last level or next to last level or both these levels together. Valence electrons is not a term which is easily applied to transition elements 3 to 12 inclusive. I should not woory too much if you are able to write configurations using s,p,d, and f sub-levels.