I don't think OMSCS is that selective. Get a couple of letters from your former professors and/or bosses. Letters are supplementary, not the sole determinant. More than the letters, they likely care about your GPA and GRE.

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Jtsummers 9 hours ago | parent [-]

They don't even require the GRE. They have a very high acceptance rate but a pretty low completion rate.

	▲	sthu11182 7 hours ago \| parent [-]
		Last time I heard (like 3 years ago), the acceptance rate was 80%. The completion rate is much lower.