On Friday I set this puzzle…

Imagine the Earth is perfectly circular and has a circumference of 24,000 miles. If you had a piece of rope stretched around it, touching the floor, that rope would also be 24,000 miles long. If you were to add 3 feet to that rope and then make it hover above the ground until it’s a perfect circle again, approximately how far off the ground would it get?

If you have not tried to solve it, have a go now. For everyone else the answer is after the break….

The rope would raise 6 inches off the ground if you added 3 feet to it! Can anyone explain why and what is surprising about this answer?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called **PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

Here is a lovely puzzle sent to me by Ashley F. Solution on Monday.

Imagine the Earth is perfectly circular and has a circumference of 24,000 miles. If you had a piece of rope stretched around it, touching the floor, that rope would also be 24,000 miles long. If you were to add 3 feet to that rope and then make it hover above the ground until it’s a perfect circle again, approximately how far off the ground would it get?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called **PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

On Friday I posted this puzzle…..

What do the following words have in common?

DEFT

FIRST

CALMNESS

CANOPY

LAUGHING

STUPID

HIJACK

If you have not tried to solve it, have a go now. For everyone else the answer is after the break.

Each of the words has 3 consecutive letters from the alphabet! Did you solve it?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called **PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

Solution on Monday.

What do the following words have in common?

DEFT

FIRST

CALMNESS

CANOPY

LAUGHING

STUPID

HIJACK

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called **PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

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On Friday I set this puzzle….

Imagine a test with 26 questions. When you get a question wrong you are deducted 5 points. When you get a question right you are given 8 points. If you answered all of the questions, and had a final score of 0 points, how many questions did you answer correctly?

If you have not tried to solve it, have a go now. For everyone else the answer is after the break.

You answered 10 correctly – but can anyone explain why?

**PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

Solution on Monday.

Imagine a test with 26 questions. When you get a question wrong you are deducted 5 points. When you get a question right you are given 8 points. If you answered all of the questions, and had a final score of 0 points, how many questions did you answer correctly?

**PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

First, if you are around Edinburgh, I am giving a talk tonight at the International Magic Festival on the psychology of magic and illusion. Details here.

Second, on Friday I set this puzzle…

A long playing record has a 12 inch diameter. The unused bit in the middle is about 4 inches in diameter, and there is a smooth outer edge one inch wide around the recording. If there are 91 grooves to the inch, roughly how far does the needle move during the recording?

If you have not tried to solve it, have a go now. For everyone else the answer is after the break.

About 3 inches – can anyone explain why?

**PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.

Solution on Monday.

A long playing record has a 12 inch diameter. The unused bit in the middle is about 4 inches in diameter, and there is a smooth outer edge one inch wide around the recording. If there are 91 grooves to the inch, roughly how far does the needle move during the recording?

**PUZZLED** and is available for the **Kindle **(UK here and USA here) and on the **iBookstore** (UK here in the USA here). You can try 101 of the puzzles for free here.