How many US nickels would you need to make a stack 100 inches tall?

According to the US Mint, nickels are 1.95 mm thick. A US inch is equivalent to 25.4 mm so 100 inches are 2540 mm.

Dividing those two numbers, 2540/1.95 = 1302.56, so you'd need 1303 nickels to make a stack at least 100 inches tall.