Question

Barb’s Grandma is always creating math problems for her to solve. In one problem she gave Barb a store receipt that listed 72 identical items, each the same price, for a total cost of $*67.9* Barb’s grandma covered the first and last digits of the total price on the receipt with stars. Determine the value of the digits that Barb’s Grandma covered.

Answer 1

9514 1404 393

Answer:

367.92

Explanation:

72 = 9·8

In order for the total cost to be divisible by both 8 and 9, it must meet a couple of requirements:

• The sum of the digits must be divisible by 9.
• The last three digits must be divisible by 8.

In order for the sum of digits to be divisible by 9, the first and last digits must total 5 or 14. (The total of existing digits is 22. The sum needs to be 27 or 36.)

In order for the last three digits to be divisible by 8, the last digit must be 2*. So, the first digit must be 5-2=3.

The first digit is 3; the last digit is 2.

The total cost is 367.92. Each item price is 367.92/72 = $5.11.

_____

* 790/8 = 98.75, so (790 + 2)/8 will be 99. 792 is the only number starting with 79 that is divisible by 8.