Negative Percent

[paulocsm]

I'm comparing 2 numbers in percent:

A1 = 10.000
B1 = 10

=(A1-B1)/B1

Result: 99.900%

But if I invert values:

A1 = 10
B1 = 10.000

=(A1-B1)/B1

Result: -99.90%

In this case, whats the Excel formula to result -99.900%?

I can do +200% but I can't -200%. Why?

-100% is limit on the downside?