The tournament starts with 150 players.

After first round 75 remain (75 matches are held & 75 players are eliminated).
After second round 38 remain (37 matches are held & 37 players are eliminated, 1 qualifies directly to next round)

Similarly, after third round 19 remain.(19 matches)

After fourth round, 10 remain.(9 matches)
After fifth round 5 remain.(5 matches)
After sixth round 3 remain.(2 matches)
After seventh round (in which 1 match is held): 1 player is eliminated, and 2 remain.
After eighth round (in which 1 match is held): 1 player is eliminated, and 1 remain.

So, total number of matches = 75 + 37 + 19 + 9 + 5 + 2 + 1 + 1 = 149