This is a public service announcement on behalf of strangers to the capital.
One sure way to tell if someone is a visitor to London is to listen to them talking about bus routes. If they refer to the one hundred and eighty six (or - worse! - the one hundred eighty six) or the seven three, they probably haven't been here long.
Here are some rules to make you sound like a native (at least here in the North West).
Refer to routes with numbers under a hundred just as normal numbers; so:
73: seventy three
82: eighty two
C11: C eleven
Once you get over a hundred, the rules get a little more complicated. If the number's not a multiple of ten, then just list its digits:
183: one eight three
113: one one three
102: one oh two (not one zero two)
If the number's over a hundred and a multiple of ten, then you need to combine the two rules above:
460: four sixty
210: two ten