So everytime I heard the word smallest natural number of 5 digits for example I do this in my head:
100000... ^ |
which means that there must be a one in there:
So I type in 1000 and then add more digits to have $$1000\,9999\,9999$$
Now into my calculator I calculated that this is is not 80 rather just 73, so I'll have to add a 7 out there to have $$1007\,9999\,9999$$
But is my answer correct? If not why my method fails and what is the correct method?