conversations.from: human
conversations.value: Rocco stores his coins in piles of 10 coins each. He has 4 piles of quarters, 6 piles of dimes, 9 piles of nickels, and 5 piles of pennies. How much money does Rocco have?
  Can you solve this problem?
conversations.from: assistant
conversations.value: Each pile has 10 coins, so he has:
  10 * 4 * $.25 = $10.00 worth of quarters,
  10 * 6 * $.10 = $6.00 worth of dimes,
  10 * 9 * $.05 = $4.50 worth of nickels, and
  10 * 5 * $.01 = $0.50 worth of pennies.
  Altogether he has $10.00 + $6.00 + $4.50 + $0.50 = $21.00