I think “one IN a million” is the more common usage in American English.
Technically, “one in a million” and “one to a million” differ. The latter is 1/1000001000000 smaller.
I think “one IN a million” is the more common usage in American English.
Technically, “one in a million” and “one to a million” differ. The latter is 1/1000001000000 smaller.