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

Posted in Brain Teasers

Counting Squares

How many squares of any size are in this grid?

4 x 4 grid

30.

There are:

16 1×1 squares
9 2×2 squares
4 3×3 squares
1 4×4 square (the whole shape)

Hence, 16 + 9 + 4 + 1 = 30.

Posted in Brain Teasers

Famous for the Friendly Folk

I have palms but not on hands,
I offer foods from distant lands,
When at my peak you’ll see me smoke,
I’m famous for my friendly folk,
My flowers grow and yet they lay,
There’s fire where a man will play,
I’m sure you know we’re family,
You’re welcome to come stay with me.

What am I?

Hawaii.

Posted in Riddles

Long Legs Crooked Thighs

Long legs, crooked thighs,
Little head and no eyes.
No burn, make a ting,
Use hands, but no ring.

What am I?

A pair of tongs.

Posted in Riddles

To Be Gold Is Good

To be gold is to be good,
To be stone is to be nothing,
To be glass is to be fragile,
To be cold is to be cruel.

What am I?

A heart.

Posted in Riddles
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Liquid In Nature

I am liquid in nature,
But don’t bend me to far,
For then I may break
And give you a scar.

What am I?

Glass. Technically, glass is an amorphous solid, but that doesn’t have the same ring to it.

Posted in Riddles
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A Tasty Fruit

I am a tasty fruit that provides you with healthy nutrients. I can also be found on a calendar. What am I?

A date.

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Leaving Home

A man leaves home, turns left, goes straight, turns left again, goes straight and turns left once more then returns home and there’s another man with a mask on. What’s going on?

A baseball game.

Posted in Brain Teasers

Travel a Lot Meet Both Rich and Poor

I travel a lot and meet both the rich and the poor, but nobody knows where I am going next. I’m invisible but you can see what I do. Who or what am I?

Wind (or anything blown by the wind). It moves all over, reaches the rich and the poor equally and no one knows exactly which way the next gust of wind will blow. You can’t see the wind, but you can see what it blows, like leaves or dust.

Posted in Riddles
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Black We Are And Much Admired

Black we are and much admired,
men seek us if they are tired,
We tire the horse, comfort man,
guess this riddle if you can.

Coal.

Posted in Riddles