What is the value of a bond that has an 8% coupon (annual payments), a 4-year maturity, and a principal of $1,000, if yields on similar securities are 10%.

annual payments=(1000*8%)=$80

Hence value of bond=annual payment*Present value of annuity factor(10%,4)+$1000*Present value of discounting factor(10%,4) =$80*3.169865446+$1000*0.683013455

which is equal to =$936.60

I just want to know how to get 3.169865446 and 0.683013455