Replace String with increasing numer [SOLVED]

[perfringo]

Iteration of ideas already provided (can't be blamed as efficient but easy to write :-):

from itertools import count

paragraph = (
    "This example is an example on how to make an example with the"
    " word example. the example ends here with an example. for example")

counter = count(1)

while 'example' in paragraph:
    paragraph = paragraph.replace('example', f"{next(counter)}", 1)

print(paragraph)

Output:
This 1 is an 2 on how to make an 3 with the word 4. the 5 ends here with an 6. for 7