What is the First Number of the Sequence?

If a number in a numeric sequence is 17 and the second number is 3, what is the first number?

I hesitated to add this because it’s poorly worded, ambiguous and the answer could be almost anything. I prefer teasers with a single answer, but there you go.

If you came up with a different answer and can explain how you did it, don’t think you’re wrong. It’s probably just as valid. Feel free to share yours in the comments.

My answer for the first number is 2.

Here’s how I got it.

The generic rule for a number in the sequence is: 2^(n – 1) + 1, where n is the position in the sequence.

Note: The teaser doesn’t specify the position of 17. In this case, it’s fifth.

Position 1: (so n = 1) is 2^(1 – 1) + 1 = 2

Position 2: 2^(2 – 1) + 1 = 3

Position 3: 2^(3 – 1) + 1 = 5

Position 4: 2^(4 – 1) + 1 = 9

Position 5: 2^(5 – 1) + 1 = 17

For the curious, the next 5 numbers of the sequence would be:

Position 6: 2^(6 – 1) + 1 = 33

Position 7: 2^(7 – 1) + 1 = 65

Position 8: 2^(8 – 1) + 1 = 129

Position 9: 2^(9 – 1) + 1 = 257

Position 10: 2^(10 – 1) + 1 = 513

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I Wave But Never Say Goodbye

I wave my hands at you,
But I never say goodbye.

You’re always cool with me,
Even cooler when I’m high.

What am I?

An electric fan

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A Ring But No Finger

What has a ring but no finger?

A telephone or alarm.

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Favorite Use Is Attached To A String

A three-letter word I’m sure you know,
I can be on a boat or a sleigh in the snow,
I’m pals with the rain and honor a king,
But my favorite use is attached to a string.

What am I?

A bow. It has three letters, the bow of a boat is the front, bows are found on the presents on Santa’s sleigh, rainbows come with the rain, one bows before a king and a bow and arrow requires a string.

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One Way I’m Feeling Normal

One way I’m feeling normal,
Another I’m extremely thin,
I could be a punishment,
Or the type who always wins.

I’m free from all impurity,
And you may have divined,
I have a keen edge,
But of course I am refined.

Fine.

The riddle refers to a variety of meanings of the word fine.

Feeling normal refers to when you feel fine.
Extremely thin refers to a fine thread.
A punishment refers to being charged a fee.
The one who wins refers to an athlete who is physically trained and hardened close to the limit of efficiency.
Free from impurity refers to measuring the fineness of precious metals.
A keen edge refers to a knife with a fine edge.
Refined refers to fine manners or elegance.

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In A Dark Room with a Rope and a Pencil

Imagine you are in a dark room with a locked door. All you have with you is a rope and a pencil. You can hear the rain outside, but there
are no windows. How do you get out?

Stop imagining.

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More You Take Away, The Bigger I Get

The more you take from me, the bigger I get. What am I?

A hole.

This is quite similar to It Cannot Be Seen and Weighs Nothing.

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100 Less Than 99

Where do you find that 100 is less than 99?

On a microwave. Most microwaves will run for a minute if you enter 100, but will run for a minute and 39 seconds if you enter 99.

100 is also less than 99 in an ordered ranking, where 1 is first, and 100th is a lower rank than 99th place.

Posted in Brain Teasers

I Can Sound a Gong

I’m in bowling and baseball,
For better or for worse,
On a match (but not the sporting kind),
I can sound a gong,
And I’m gone.

What am I?

Strike.

A strike in bowling is good. In baseball it’s good for the pitcher but not for the batter. You can strike a match to light it. When the clock strikes one a gong sounds and when you strike a paragraph, it’s gone.

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What Runs Around the Yard

What runs around the yard without moving?

A fence.

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