My back-of-the-envelope calculation is several hundred billion dollars a year.

Archer did a few quick back-of-the-envelope calculations in his head.

We did the back-of-the-envelope calculations and thought, too, we can share a mortgage.

My conclusions based on his almost back-of-the-envelope calculation should be taken even more cautiously.

Critics said that their back-of-the-envelope calculations showed a much less pronounced impact on fuel economy.

According to my back-of-the-envelope calculations, they averaged 49.83 on Sunday.

His back-of-the-envelope calculations indicate it may be feasible, although he is far from being ready to demonstrate how.

Levenspiel is known for his ability to perform quick back-of-the-envelope calculations.

So if we just, quick back-of-the-envelope calculation, that gives us three attempts essentially per minute.

Care to give a back-of-the-envelope calculation of why that particular timeframe?