Denominations: Rs. 50, 100, 200, 500, 2000

Total number of denominations = 5

We need to select at least 3 denominations.

Number of ways to select 3 denominations from 5 = $C(5, 3) = \frac{5!}{(3! \cdot 2!)} = 10$

Number of ways to select 4 denominations from 5 = $C(5, 4) = \frac{5!}{(4! \cdot 1!)} = 5$

Number of ways to select all 5 denominations = $C(5, 5) = \frac{5!}{(5! \cdot 0!)} = 1$

Total possible sums = $10 + 5 + 1 = 16$