What should your bankroll be?

What would be a good size bankroll if you played various multi table tourneys. Buy in's between $20-$50. Thank you for your responses

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like 100 buyins? lots of variance in MTT.. maybe 100 isn't even enough.

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Oh.. and there are a ton of threads about this.. try and learn to use the search function. It sucks, but once you get used to it it's alright.