How many lightning bolts strike the United States each year? (Thanks to Kandice Carter of the Thomas Jefferson National Accelerator Facility for suggesting the question.)

How many grams of carbon are needed to print the text of a 400-page book? (Thanks to Evan Jones, Sierra College emeritus, for suggesting the question.)

Look for the answers online at under “Browse,” at the very end of the current issue.

Question suggestions are always welcome!

For more Fermi questions and answers, see Guesstimation 2.0: Solving Today’s Problems on the Back of a Napkin, by Lawrence Weinstein (Princeton University Press, 2012).

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