In Excel 2007:

I've noticed that the VLOOKUP and the equivalent INDEX & MATCH functions
treat .7 + .1 as something less than .8

Example:

Given the Range...

60% A
70% B
80% C
90% D

The formulas...
=VLOOKUP(.7,Range,2) returns B
=VLOOKUP(.8,Range,2) returns C
=VLOOKUP(.8+.1,Range,2) Returns D
as they all should.

However, the formula...
=VLOOKUP(.7+.1,Range,2) returns B.
or,
=VLOOKUP(.7+.1,Range,2,false) returns #N/A.

Certianly work arounds are possible, however it would seem that this is an
error on the part of Excel. Can anyone verify? How would one submit a bug
report to MS if it's even possible?