Help in < or mathematical excel equations
 

In one formula, if your input cell is D1:
=LOOKUP(D1,{-1E+307;0.01;1;10},{"invalid";0.2;0.4;"invalid"})

For better maintenance you can put into A1:B4
-1E307 invalid
0.01 0.2
1 0.4
10 invalid

=LOOKUP(D1,A1:A4,B1:B4)

Please notice that here the implicit comparisons are <1 resp. <10 (and
not <.99 and <9.99).
If this is what you thought it should be then LOOKUP may be your
choice.

Regards,
Bernd