formula for number of goods bought - HELP!!

[MO987654]

I want to create the following formula but not sure which syntex to use.
We sell goods, the more you buy the cheaper they get. So if you buy 1-24
peices they cost £142 each, if you buy 25-99 they go down 10% to £128 and so
on.
I need to create a running total with this information.
So Mr X buys 10 pieces in Jan (so he is paying £142) but in Mar he buys 25
(so his price reduces to £128). How can I write this as a formula.
Thanks

 

[Bob Phillips]

=K1*142*LOOKUP(K1,{0,25,100},{1,0.9,0.75})

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HTH

Bob


(there's no email, no snail mail, but somewhere should be gmail in my addy)

 

[Gary''s Student]

Put the quantity in A1 and in B1:

=A1*IF(A1<25,142,128)

So to buy 24 will cost 3408
so to buy 25 will cost 3200