EXAMPLE A:
Seat 1 posts 200 small blind.
Seat 2 posts 400 big blind.
Seat 3 raises to 1000 (a raise of 600).
Seat 4 raises to at least 1700 (1000 + 100 above a minimum raise of 600 =700).
Seat 5 raises to 2300 (1700 + minimum raise of the first raise = 600)

OR IS THIS CORRECT??

EXAMPLE B:
Seat 1 posts 200 small blind.
Seat 2 posts 400 big blind.
Seat 3 raises to 1000 (a raise of 600).
Seat 4 raises to at least 1700 (1000 + 100 above a minimum raise of 600 =700).
Seat 5 raises to 2400 (1700 + minimum raise of the last raise = 700)
THE ANSWER
Seat 1 posts 200 small blind.
Seat 2 posts 400 big blind.
Seat 3 must raise to at least 800 and raises to 1000 (a raise of 600).
Seat 4 raises to at least 1600 (1000 a minimum raise of 600 =1600).
I don't know where your 100+ figure comes from.
Seat 5 raises to at least 2200 (1600 + minimum raise of the last raise = 600)

If Seat 4 raises to 1700
Seat 5 must raise to at least 2400 (1700 + minimum of the last raise = 700)