Dental floss is used to help prevent the formation of dental plaque before it calcifies to form calculus (or tartar). A typical single pack contains about 50 m (55 yd) of thread.

In June 1994, an inmate in a West Virginia high-security (!) facility used several containers of floss to escape. Two days prior to his escape, he had used multiple strands to form a “rope” as thick as a telephone cord and used it to scale a 5.5-m (18-ft) cinder block wall and hung from it while cutting through the fence with an 8-cm hacksaw blade. The whole episode took about 20 minutes, and he was not recaptured for 41 days. Jail authorities voted to install razor wire above recreational areas after his escape. They also stopped selling dental floss to inmates.

Estimate how many packs of floss he used.

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