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

I Cover What Is Real And Hide What Is True

I cover what is real and hide what is true,
But sometimes I bring out the courage in you.

What am I?

A mask. It makes people look different, but can make you feel more powerful than you normally do.

Makeup also works.

Posted in Riddles

Reaching As High As Your Neck

Reaching as high as your neck, waist, or knees,
The going gets slower when wading through these.

What are they?

Shallows

By Sef Daystrom

Posted in Riddles

Liquid Splashes But None Seeps Through

When liquid splashes me, none seeps through,
When I’m moved a lot, liquid I spew,
When I am hit, color I change,
And colors I come in, quite a range,
What I cover is quite complex,
Yet I am very easy to flex.

What am I?

Skin

Posted in Riddles
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Show Your Work

Solve this one carefully!

230 – 220 x 0.5 = ?

You probably won’t believe it, but the answer is 5! How can this be true?

The answer is 120, and 5! = 5 × 4 × 3 × 2 × 1 = 120

Credit to John May for this one.

Posted in Brain Teasers

Captain Mark

Captain Mark is the captain of the ship. The captain of the ship is Captain Mark. The ship has plenty of space.

What is the name of the ship?

The Space Shuttle Endeavour, captained by Mark Kelly.

I received this by email from someone who didn’t know the answer. Thanks to Devon for helping with this answer.

Posted in Riddles

I Go Around In Circles

I go around in circles,
But always straight ahead
Never complain,
No matter where I am led.

A wheel.

Posted in Riddles

Four Legs and a Foot

What has four legs and a foot, but can’t walk
And a head but can’t talk?

A bed. The foot of the bed can’t walk and the head of the bed can’t talk. It’s probably a good thing that beds can’t walk and talk. Just think of where they’d go and what they’d say…

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A Fruity Series

What is the next letter in this fruity series?

a a a p p ?

Y.

The series consists of the letters of papaya in alphabetical order.

Posted in Brain Teasers

Thirty White Horses On A Red Hill

Thirty white horses on a red hill,
first champ, then stamp, and then stand still

Your teeth.

Posted in Riddles