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The 22nd and 24th Presidents of the U.S.

The 22nd and 24th presidents of the United States of America had the same parents, but were not brothers. How is this possible?

It was the same guy! Grover Cleveland is the only president in history to serve two, non-consecutive terms.

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Kevlar, Fire Escapes and Wipers, Oh My!

What do computer compilers, kevlar, fire escapes and windshield wipers all have in common?

They were all invented by women.

A variation of this brain teaser includes laser printers (they were invented by Gary Starkweather) and bulletproof vests (invented by Casimir Zeglen using silk, though modern vests use Kevlar, so it’s halfway right).

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Sixteen, Twenty-six, Then What?

Fill in the missing numbers in this number series.

16, 26, ?, 43, 50, ?, 61, 65, ?, 70, 71

The method to create the series is start by adding 10, then decrease the addend by 1 for each new number in the sequence. That gives us:

16 + 10 = 26
26 + 9 = 35
35 + 8 = 43
43 + 7 = 50
50 + 6 = 56
56 + 5 = 61
61 + 4 = 65
65 + 3 = 68
68 + 2 = 70
70 + 1 = 71

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The Tail of a Dragon

What animal can be created from the head of a lamb, the body of a pig, the hind quarters of a buffalo and the tail of a dragon?

A lion.

Head of a lamb = L
Body of a pig = I
Hind quarters of a buffalo = O
Tail of a dragon = N

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Twice the Sum of Its Digits

What number is twice the sum of it’s digits?

18.

1 + 8 = 9
2 × 9 = 18

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When Is The Equation Correct?

When is the following equation correct?

14 + 1 = 3

When dealing with 24-hour time, 1400 hours plus 1 hour is 1500 hours, also known as 3 o’clock.

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Rearrange My Letters To Be Clean

Rearrange these letters into something you can clean with.

boas

soap (by flipping the b upside down, similar to how IHOP became IHOb)

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Rebellious Randall

You’re waiting to board your flight at the airport with 99 other passengers, each with an assigned seat. All but one of the passengers will gladly sit in their designated seat. The only exception is Randall, a scoundrel who refuses to follow the rules. When he boards, he will choose a random, unoccupied seat.

If a rule-following passenger finds someone in their spot, they will choose another one at a random from the remaining unoccupied seats.

What is the probability that the last person to board the plane will sit in their proper seat?

The randomness stops as soon as someone else sits in Randall’s assigned seat. The chances of this happening range from 1 out of 99 to 1 out of 1 (when only one seat remains).

Thus, the probability of the last person sitting in their own seat can be calculated as 1/99 plus the sum of 2 to 98 of the formula 1 / n × (n + 1), which works out to 0.5, or 50%.

So there’s a 50% chance the last passenger will sit in their own seat thanks to Randall for screwing up order and procedure when boarding an aircraft.

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Spell Eighty

How can you spell eighty with only two letters?

A-T (pronounced eighty).

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A Square and a Cube

What two-digit number is the square of one number and the cube of another?

64

82 = 64
43 = 64

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