ROUNDDOWN function in IF formula.. ?

[jamieblue]

Hi, I'm new to these forums sorry and have a couple of questions about some stuff - hope they're not too annoyingly easy for you..

Anyway, I think the first one is probably easier. I've got this set of 12 initial possible values, quite simply 1-12. However each one must correspond with a different value. I was thinking of doing a nested IF? But I believe they only go up to 7 so didn't think it was possible.

I need 1 to have a corresponding value of 5, 2 -> 10, 3 -> 15.... in this sequence up until 8, but then 9 needs to be 50, 10 -> 60, 11 needs to be 75 and 12 -> 90..

I mean I could put the corresponding values in myself obviously, but this takes effort cause the inital values of 1-12 will always be changing..

The second thing is, once I (hopefully) have done this, I then times the corresponding value (i.e. 5, 10, 15) by a constant - but the problem is some of the new numbers generated need to be rounded down (actually changed, not formatted) by 0.5. i.e. the constant is 90, and if I use my equation I get 4.5 for 5 (I know complicated equation right? :P), 13.5 for 15 etc, that need to be rounded down to 4, 13 etc. But using the other values, obviously all even numbers except for 9, i get numbers with no decimal places, that I want to keep as they are. I've tried the IF function as well as ROUNDDOWN thing with it, but it seems hard with so many values. I tried some stuff with ISODD and ISEVEN with the nested IF with AND and ROUNDUP and stuff, but I wasn't sure how to 'keep' a value of a cell, like all those that are fine that don't have decimal places - but I really don't think I'm doing the right thing. Is this even possible what I'm asking?! I hope you can understand what I mean :P

Anyway, thanks in advance if anyone offers any support