about
you must be about fifty

aye
fifty-five ayes and thirty noes

fifty
cinquenta

fifty-fifty
a fifty-fifty chance

get on for
he's getting on for fifty

intervene
fifty years intervened

pass
he's passed the fifty mark

there
fifty miles there and back

verge on
to verge on fifty

verge upon
to verge on fifty

wrong
on the wrong side of fifty