Question: How can you measure something to see if it is about 6 inches long without a ruler?
Options:
Place a Dollar (Or other American Bill) beside the item.  A bill is about 6 inches - 2 of them is about a foot.
Place a quarter (Or other American coin) beside the item.  A coin is about 6 inches - 2 of them is about a foot.
Answer: Place a Dollar (Or other American Bill) beside the item.  A bill is about 6 inches - 2 of them is about a foot.