[osreb]

2. Q: Did you ever wonder why dimes, quarters and half dollars have notches, while pennies and nickels do not?
A: The US Mint began putting notches on the edges of coins containing gold and silver to discourage holders from shaving off small quantities of the precious metals. Dimes, quarters and half dollars are notched because they used to contain silver. Pennies and nickels aren't notched because the metals they contain are not valuable enough to shave.