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प्रश्न
Evaluate `(n!)/((n-r)!)` when n = 6, r = 2
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उत्तर
when n = 6, r = 2 `(n!)/((n-r)!) = (6!)/((6 - 2)!) = (6!)/(4!) = (6 xx 5 xx 4!)/(4!) = 30`
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