Odds Calculations

[PJM1206]

I was trying to calculate the odds of winning a KENO bet. I picked 4 numbers 2,10,13,23. There are 80 possible numbers that can come up 1 through 80. The ticket cost $1.00 and pays $1 if two numbers hit, $4 if 3 numbers hit and $100 if all 4 numbers hit. I calculated the odds of 2 numbers coming up as 499 to 1: 4/80*3/79*76/78*75/77=.002 or 499:1 and the odds for all 4 numbers 4/80*/3/79*2/78*1/77= .000006 or 158M :1??? Is that correct?