There's one small caveat in the "two tickets double your chances of winning" thing, and that is that the tickets must have different numbers on them. If, say, you bought 2 lucky dips and they both drew the same numbers, then your chances of winning are still 1 in 120m.
(In this scenario you...
Yes, yes it does.
Buying 2 tickets instead of 1 does double your chances of winning because 2 is double 1. If you then bought another, your chances would be 3/120. Your 7 ticket scenario would give you a 7/120 chance.
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