maths question help

i am not much of a maths guy but I have been working on and have been flat betting a system I came up recently but am thinking of turning it into a 4 game chase.....to lose the chase a +200 underdog would have to win 4 times in row....anyone know what the chances of this happening are? therefore what are my chances of losing the 4 game chase....thanks in advance...

when a dog is +x then the probability of it winning the game is

10000/(100+x) that is for x=+200 : 10000/300=33,33%

if it goes to win 4 times in a row them you have o.3333 to the power of 4 , that is 1,23%

https://g.sportsdatabase.com/mlb/query?sdql=line%3E200+and+season%3E2006&submit=S+D+Q+L+!


26,3% winning percentage after 2006 or 0,478% for 4 in a row.
interesting result: blindly playing dogs +200 you lose (do not think that playing favs at -260 willbe any better!