This is a completed example but I want to know where the numbers come from. How is discount factor found and how is the discounted cash flow found, and then how do you solve for the discount payback period?

Microsofts DPBP(discount factor of the electronics industry)

Year	Cash Flow	Discount Factor	Discounted Cash Flow	Cumulative Discounted Cash Flow
1	23.72	0.9270	21.99	21.99
2	24.98	0.8594	21.47	43.46
3	31.38	0.7967	25.00	68.46
4	32.25	0.7386	23.82	92.28
5	38.26	0.6847	26.20	118.47

DPBP = 2 + [(51.67 43.46)/ (68.46 43.46)]

DPBP = 2 + 0.33

DPBP = 2.33 years