question: A candle melts by 2 centimeters every hour that it burns. How many centimeters shorter will a candle be after burning from 1:00 PM to 5:00 PM?
answer: The candle burns for 5 - 1 = <<5-1=4>>4 hours.
  Thus, the candle will be 2 * 4 = <<2*4=8>>8 centimeters shorter.
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