Question

Toenails grow at an average rate of about 0.05 mm per day, and the average toenail is about 3/4 inch long. About how many months does it take for a toenail to completely regenerate itself?

Answer 1

0.05 mm * ? days = 0.75 inch

Use proportions

1 mm = 0.0394 inch
0.05 mm = 0.00197 inch

0.75 inch / 0.00197 inch = 380.71

380.71 days / 30 days = 12.7 months