Cornelius and the Flat Tire

Cornelius got a flat tire on a miserable, rainy day. As he was changing it on the side of the road, he placed the four lug nuts in the overturned hub cap. As our dear friend was moving back to put on the spare, he accidentally bumped the hub cap. He watched helplessly as all four lug nuts rolled into a deep sewer and were whisked away. Then our friend had a brilliant solution and within minutes was driving safely away.

What was his solution?

He removed one lug nut from each of the other 3 tires and used them to secure the spare tire, then drove to a tire shop.

Posted in Brain Teasers

Winning at Wimbledon

As a result of temporary magical powers, you have made it to the Wimbledon finals and are playing Roger Federer for all the marbles. However, your powers cannot last the whole match. What score do you want it to be when they disappear, to maximize your chances of hanging on for a win?

It sounds obvious that you should ask to be ahead two sets to love (it takes 3 out of 5 sets to win
the men’s), and in the third set, ahead 5-0 in games and 40-love in the sixth game. (Probably you
want to be serving, but if your serve is like mine, you might prefer Roger to be serving the sixth
game down 0-40 so that you can pray for a double fault.)

Not so fast! These solutions give you essentially 3 chances to get lucky and win, but you can
get six chances—with three services by you and three by Roger. You still want to be up two sets
to none, but let the game score be 6-6 in the third set and 6-0—in your favor, of course—in the
tiebreaker.

Credit goes to Peter Winkler for creating this.

Posted in Brain Teasers

A Black Dog Night

A completely black dog was strolling down main street during a total blackout affecting the entire town. Not a single streetlight had been on for hours. As the dog crosses the center of the road a Buick Skylark with two broken headlights speeds towards it, but manages to swerve out of the way just in time. How could the driver see the dog to swerve in time?

It was during the day.

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When I Point Up It’s Bright

When I point up, it’s bright.
When I point down, it’s dark.

What am I?

A light switch

Posted in Riddles
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How Old is Lilly?

Two days ago Lilly was 7 years old. Next year she will turn 10. How can this be?

Her birthday is December 31st. Today is January 1st so she was 7 two days ago, and turned 7 last year. Now she’s 8 and will turn 9 this year. And next year she’ll turn 10.

For example, if today is 01 Jan 2015:

30 Dec 2014 = age 7 (two days ago)
01 Jan 2015 = age 8 (today, she turned 8 on 31 Dec 2014, which was last year)
31 Dec 2015 = age 9 (her birthday this year)
31 Dec 2016 = age 10 (her birthday next year)

Posted in Brain Teasers

The Mystery Six-Digit Number

Find a six-digit number containing no zeros and no repeated digits that satisfies the following conditions:

1. The first and fourth digits sum to the last digit, as do the third and fifth digits.
2. The first and second digits when read as a two-digit number equal one quarter the fourth and fifth digits.
3. The last digit is four times the third digit.

192768.

If you call the number ABCDEF, then you get the following equations.

1. A + D = F and C + E = F
2. AB = DE / 4
3. F = 4 × C

The only numbers that work for C and E are 2 and 6 or 4 and 8, and in order to make F a single-digit number, we can deduce that C = 2, E = 6 and F = 8.

So far, our number is AB2D68.

We know A + D = 8 so A and D are both odd numbers. The only odd number less than 8 that we can use for D to make one-quarter of two-digit number D6 also be a two-digit number is 7, so D = 7 and A is 1. This makes the two-digit number AB 19.

Posted in Brain Teasers

New Door

Rearrange the letters in the words “new door” to make one word.

“new door” can be rearranged into “one word”

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I Am a Protector

I am a protector.
I sit on a bridge.
One person can see right through me.
Others wonder what I hide.

What am I?

Sunglasses

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Three Two Three Sequence

What number belongs at the beginning of this sequence?

?, 3, 2, 3, 9, 2, 4, 8, 4, 3, 7, 6

3 ½.

If you break up the numbers into groups of 4, a,b,c,d, then 2 × |a – d| = |b – c|.

9 2 4 8 → 2 × |9 – 8| = |2 – 4|, or 2 × 1 = 2
4 3 7 6 → 2 × |4 – 6| = |3 – 7|, or 2 × 2 = 4, so
n 3 2 3 → 2 × |3 ½ – 3| = |3 – 2|, or 2 × ½ = 1;

I’m not sure this is the correct solution, but it’s the best I’ve found so far. Email me if you know of a better one.

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Not in Any State

Which letter of the alphabet is the only one that does not appear in any of the names of the 50 United States?

The letter Q.

Posted in Brain Teasers