sufficient postage?

I just mailed a large envelope with 82 sheets of paper in it, to my CPA.

I didn't want to have to drive to the post office, and I don't have access to a letter scale in my building, so I looked online and found estimates ranging from 5.5 to 6.0 sheets of printer paper per ounce.

I then went to the USPS website and found that they charge 17 cents per ounce after the first ounce. 82 / 5.5 = 14.9 ounces, so rounding up to 15 ounces, that would seem to imply needing $3.21 worth of postage.

I looked up the current price of first class postage (turns out it's 42 cents) and calculated that I would need 8 stamps x 42 cents = $3.36 to exceed $3.21. I had exactly 8 stamps in my wallet. If only things always worked out so well!

Now I'm just hoping that all those estimates and calculations were at least good enough to get my letter to its destination. I guess we'll see!