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75 votes

Born on the same day, but one is two years older

We'll just apply a bit of science assuming they were born in same year as well:
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  • 959
68 votes
Accepted

Measure 22 minutes with 7 and 13 minute hourglasses

A very simple solution, taking is to A better solution takes only How?
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62 votes
Accepted

A clock correct three times a day

Since a stopped clock already agrees with a correctly running clock twice per day, So the answer (that requires the smallest clock hand speed) is Since the answer must be symmetrical (as long as the ...
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  • 69.3k
56 votes

My birthday is uncommon

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50 votes
Accepted

My birthday is uncommon

It is
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47 votes
Accepted

Born on the same day, but one is two years older

They were born on
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  • 69.3k
46 votes

Born on the same day, but one is two years older

Apply some other bit of science, assuming they were born at the same time,
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  • 561
45 votes

Older twin's birthday is one day after younger's

Foo is older than Bar, but celebrates his birthday the day after Bar because one of the following happened:
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37 votes

Born on the same day, but one is two years older

Is it lateral-thinking?
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  • 3,070
32 votes

My birthday is uncommon

Similar to Daniel's answer but a slight variation:
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30 votes

A clock correct three times a day

Suppose we have an accurate clock and the fast clock, and that they start off showing the same time. Here is an alternative method:
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29 votes
Accepted

Aging A Lot Faster

The day is Reasoning: Classic Mind Puzzle :) My fav <3
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  • 7,482
28 votes
Accepted

A man is born in 1955

The answer is simply: I have heard this one before but I don't remember where, maybe the movie you mentioned.
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  • 941
26 votes
Accepted

How often does a digital watch show a palindrome?

Let us denote the time by AB:CD:EF, where AB is between 00 and 23, CD and EF are each between 00 and 59, and of course A=F, B=E, C=D. The middle two digits Since ...
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24 votes
Accepted

All clock hands at equal degrees from each other

At noon, all three hands are at $0$ degrees from each other. Let's say the Moment of Truth is after the hour hand has moved around $x$ degrees. In that time, the minute hand moves $12x$ degrees and ...
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24 votes

Measure 22 minutes with 7 and 13 minute hourglasses

22 minutes with lateral thinking (though the accepted answer is better)
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  • 943
24 votes

A man is born in 1955

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23 votes

Older twin's birthday is one day after younger's

Because they are... And they were born... And...
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  • 1,378
23 votes

A clock correct three times a day

Alternative method: The answer to how fast the clock must go:
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  • 331
22 votes
Accepted

Full-sized ice cubes

First produce 48 by putting the traces up/down/up/down/up in the freezer. Then use 18 of the ice cubes and put them in the corners of the botton 6 trays, produce 66 more ice cubes. Do this 2 more ...
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  • 6,874
22 votes
Accepted

Explain this holiday calendar oddity

Would it be because:
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  • 396
21 votes
Accepted

Digital Clock Brightness

Logic behind the answer: So, without really looking at anything else, my initial guess is: resulting in: Note: Edit:
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  • 2,366
20 votes
Accepted

When was I born?

You and your twin were born:
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  • 35.4k
19 votes
Accepted

Two brothers, two watches

It is currently and the older brother is How I figured this out:
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19 votes
Accepted

Using burning ropes as timer - how to measure 1 hour and 8 minutes with 3 ropes?

Ok I will present a solution. For convenience, I will number the ropes in the order of their burning. STEP ONE STEP TWO STEP THREE FINAL STEP I have successfully measured 1hour 8 minutes or 68 ...
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  • 354
19 votes
Accepted

Probability of three identical digits on a four-digit digital clock?

Number of qualifying times: Probability:
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18 votes
Accepted

Finally, you wake up from a coma

The date of the accident is Explanation
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  • 4,821
18 votes
Accepted

Riddle Man's age

The only perfect square in the 19th century is: Which would make him For the 20th century:
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  • 4,599
17 votes
Accepted

A mosquito is born at T=0 and after 2 seconds makes a new mosquito every second, how many mosquitos at T=8.5?

There are Because
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  • 9,301
17 votes
Accepted

If the second hand goes backwards, starting from 12:00, how long does it take to meet with the minute hand?

The clockface is divided into $60$ segments.
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