Is there a faster way>

Anurag@Gurome wrote:

alex.gellatly wrote:Billy has an unlimited supply of the following coins: pennies (1¢), nickels (5¢), dimes (10¢), quarters (25¢), and half-dollars (50¢). On Monday, Billy bought one candy for less than a dollar and paid for it with exactly four coins (i.e., he received no change). On Tuesday, he bought two of the same candy and again paid with exactly four coins. On Wednesday, he bought three of the candies, on Thursday four of the candies, and on Friday five of the candies; each day he was able to pay with exactly four coins. Which of the following could be the price of one candy in cents?

Note that values of the all of the coins are multiple of 5 except the pennies. Hence, if the total price of the candies is of the form (5n + 4), then we need 4 pennies alone to cover the remainder of 4. Hence, the price of one or two or three or four or five candies cannot be of the form (5n + 4)

Let us check the options accordingly,

• A. 8 --> 3*8 = 24 = (4*5 + 4) --> NO
  B. 13 --> 3*13 = 39 = (7*5 + 4) --> NO
  A. 40 --> All multiples are divisible by 5 --> YES
  A. 53 --> 3*53 = 159 = (31*5 + 4) --> NO
  A. 66 --> 4*66 = (52*5 + 4) --> NO

The correct answer is C.