it's a hundred, etc. to one that somebody/something will do something

it's a hundred to one that

It is extremely unlikely that (something will happen or be the case). They say they're working toward a solution, but with congress deadlocked they way they are, I reckon it's a hundred to one that they pass any legislation on the issue. The tech company has stated that it's a hundred to one that their new facial recognition software can be fooled by a picture or a similar-looking person.
See also: hundred, one, that

it's a million to one that

It is extremely unlikely that (something will happen or be the case). They say they're working toward a solution, but with congress deadlocked they way they are, I reckon it's a million to one that they pass any legislation on the issue. The tech company has stated that it's a million to one that their new facial recognition software can be fooled by a picture or a similar-looking person.
See also: million, one, that

it’s a hundred, etc. to one that somebody/something will (not) do something

it is almost certain that somebody/something will (not) do something: It’s a hundred to one that the train will be late.It’s a million to one that she’ll finish before us. She always does.