f(x) is O(1) means that there exists x0, M > 0 such that for all x > x0, |f(x)| <= M. Clearly, the statement still holds (for different M) if 1 is replaced by a

f(x) is O(1) means that there exists x0, M > 0 such that for all x > x0, |f(x)| <= M. Clearly, the statement still holds (for different M) if 1 is replaced by any positive number. https://en.wikipedia.org/wiki/Big_O_notation https://en.wikipedia.org/wiki/Big_O_notation