"There is only one set of winning numbers drawn and each set played is an attempt to match that set. "
Suppose you only bought one ticket but they drew two sets of numbers? What would that do to the odds?
"I didn't say each additional ticket cuts the odds in half. "
That's another part of his inability to understand 3rd grade fractions. He seems to think that we're saying that 2/100ths is twice as much as 1/100th (and might even understand that much) but also thinks that we're saying 2 x 2/100 is 3/100.
"If one PB ticket is up against 292.2 million odds and an additional ticket cuts those odds in half (so say you) then every additional tickets cuts the odds of the ticket bought just before it in half, no? "
Maybe the problem is such a pathetic grasp of 2nd grade arithmetic that he thinks that if 2 is twice as much as 1 then 3 is twice as much as 2?
"Easy game, with 100 possible outcomes. "
You could have asked what the odds are if you buy one ticket with an even number and one with an odd number, but I tried that years ago and it's apparently beyond his comprehension.
"Then scroll down to Test Your Lottery Knowledge "
Did they give you an award for getting the worst score they've ever seen?
"So we can see where the confusion comes from... original post is about odds, but title says probability "
The confusion is a problem with arithmetic, not being extremely precise about the words you interchange with probability. A lot of people (maybe even most?) don't even realize that odds aren't the ratio of the number of chances compared to the number of possible outcomes. If you can find an official lottery website that doesn't shows odd as "1 in 1000", "1 in 292,201,338 " etc, let us know.
"Because 1 out of 150M means you managed the miracle of eliminating half of all possible combinations!!! "
No, it means that you remember learning how to simplify fractions in 3rd grade. You know that if you buy 1 gallon of milk you get all 4 quarts, right?
"If all 500,000 ticket numbers are in play for the first top prize "
Do we need a 4 page thread about how raffles work? In a raffle they pick some number of entries from the total entries sold, which may be different than the number of entries that were available for sale. That's why they always have the number of winners they advertised.
"4/500,000... this is where probability stops "
Probability stops when the drawing is held and instead of a probability of things happening things have actually happened.
"I've already computed it in my head "
We've always known that's where the problems happen.