Finding closest value

[krlss26]

	A	B	C
13	250	1
14	300	0.967
15	350	0.933
16	400	0.9
17	450	0.867

I need Excel to select the appropriate row from Column B based on a number I will write on C1. This number will be between 250-450. I would like to have it matched with the closest number on Column A and then matched with B. I have this:

=LOOKUP(C13,A13:B17,2) But even if I write 399, it will give me the result for 350. I don't know how to get it to match the closest number. I have tried the MATCH command, but I couldn't figure out how.

 

[Macropod]

You could use:
=INDEX(B13:B17,MATCH(ROUND(C1/50,0)*50,A13:A17,0))

 

[krlss26]

Thank you so much!