Fifteen pennies, three nickels, two dimes, one fifty-cent piece
There are 3 ways, one of which is 1 x 50c
2 x 10c
3 x 5c
15 x 1c.
You cant unless you have 100 pennies.
I'd say you can't. If all the coins are the smallest possible without pennies, they must all be nickels, and 21 of them make $1.05 . So in order for 21 coins to be not more than $1.00, there must be some pennies.
3 dollar 3 coins
(1) $0.50 (2) $0.10 (3) $0.05 (15) $0.01
3 dimes 13 nickles 5 pennies
20 5 cents coins
Not in the US.
5*20 cents (Australian) make a dollar. In US and Canadian coins, a 50 cent piece, a quarter, two dimes, and a nickel also make a dollar.
5 dimes and 10 nickels make 1 dollar.
10 x 10c coins
21 pennies
half dollar, quarter four dimes