By setting the snooze time to 9 minutes, the alarm clock only needs to watch the last digit of the time. So, if you hit snooze at 6.45, the alarm goes off again when the last digit equals 4. They couldn’t make it 10 minutes, otherwise the alarm would go off right away, or it would take more circuitry.
A one way street sign. It tells you the correct way to go, is black and white (in the United States), going the wrong way can get you a citation and the sign only has two words on it.
Franklin lent Darlene as much money as she already had, then she spent $10. The next day, Franklin lent her as much money as she now had and again, she spent $10. On the third day Franklin once again lent her as much money as she now had and she spent $10, leaving her broke. How much money did Darlene start with?
$8.75 You may have been tempted to guess $30 because $10 is spent three times, but that would mean she would have had $60 ($30 lent plus the $30 she already had), and $50 after spending $10. The rest of the numbers end up at higher than zero, so we know it has to be less than $30. Even starting at $10 leaves Darlene with $10 on the third day. Starting with $8.75 works out as follows.
I come in the form of a question. If you don’t know the answers, you will think a lot, but when you know or you are being told the answer it sounds simple that you will think everybody can easily know.
The problem works out to a set of three equations: b + c + d = 22 a + c + e = 22 a + b + c + d + e = 30
Solving for c = 14, leaving d = 8 – b and e = 8 – a. In other words, c must be 14, but the other two numbers just have to add up to 8. The requirement that they be unique rules out 4 + 4, so you’re left to choose from the following combations for b + d and a + e: 0 + 8 1 + 7 2 + 6 3 + 5
