# How to interpret operating margin when we invest in companies?

It seems that sometimes I may get desensitized by looking at operating margin if it is 35% vs 50%, I may think it is "no big deal", but it seems:

Sold item at     COGS and expenses     Operating Margin    Net Income before tax
------------     -----------------     ----------------    ---------------------
\$13                   \$10                  23%                       \$3
\$16                   \$10                37.5%                       \$6
\$19                   \$10                  47%                       \$9
\$22                   \$10                54.5%                      \$12

So it seems, from row 1 to row 3, the operating margin doubled, but the profit before tax actually tripled.

And what's more, the operating margin cannot be above 100%... so if it get to 55% or 58%, we may think it is "no big deal", but in fact, the profit before tax might have increased a lot?

For example, when we can sell the item at \$22, the operating margin merely increased from 47% to 54.5%, so we may feel "it is only a few percent points", or 54.5 / 47 = 1.16, so it is a 16% increase, but the profit before tax actually went from \$9 to \$12, which is a good 33% increase?

And I think one good point about operating margin being so high in the 50% range, could mean, it is a business that is able to keep its pricing power, or else the operating margin has to be lower, such as 20% or 15%, so it might be a good business? On the flip side, it also means any changes to its competitive advantage, it may lose it pricing power and have a profit before tax drop from \$12 to \$6 easily, going down to half only.

Would this roughly be how to interpret operating margin? Is some concept incorrect in the above statement?