With your data in A1:K1:

=MATCH(MIN(A1:K1-45.11),A1:K1-45.11,0)

Array-entered, which means commit with CTRL+SHIFT+ENTER instead of just with
ENTER

In the formula bar, the formula will appear in curly brackets, to prove it
is an array formula

--
Kind regards,

Niek Otten

"Nick Krill" wrote in message
...
Data is random in nature and unsorted. Generally between 10 and 100, two
decimal precision (see below). How do I find the position of the entry
closest a given value, say 45.11

45.54 45.56 45.32 45.5 45.42 45.35 45.46 45.4 44.97 45 45.05