Double Puzzle

TRAVELED on two Northern Line trains yesterday, and in both cases the serial number of the carriage - one was 53537, the other 52618 - made for a Tube Puzzle that has a perfect solution, ie uses the digits in the order printed.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.

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My solutions: 5 - 3 (x 5) = 3 + 7

5 - 2 + 6 - 1 = 8

Tricky Tube Puzzle

HERE is a carriage serial number from a Northern Line train that makes an interesting Tube Puzzle: 52572.
As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the digits in the order printed.
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My solution: 5 x 2 (- 5) = 7 - 2

Tricky Tube Puzzle

SPOTTED the following serial number on a Northern Line carriage: 51618
As usual with these tube puzzles, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 8 - 5 = 6 ÷ (1 + 1)

Tube Puzzle

SPOTTED the following serial number on  a Circle Line carriage: 21497
As usual with these tube puzzles, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the digits in the order printed.
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My solution: 2 = 1 + 4 + 9 (÷ 7)

Northern Puzzle

SAW this serial number on a Northern Line carriage: 53712.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the numbers in the order they appear.
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My solution: 5 + 3 - 7 + 1 = 2

Tricky Brain Exercise

SAW this serial number on a Central Line carriage: 92136.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the numbers in the order they appear, but it is far from obvious.
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My solution: 9 ÷ (2 + 1) + 3 = 6

Tube Puzzle

SAW this serial number on a Northern Line carriage: 51519.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the numbers in the order they appear.
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My solution: 5 + (1 x 5) = 1 + 9

Brain Exercise

SAW this serial number on a Northern Line train: 52529.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 5 + 5 - (2÷ 2) = 9

Northern Perfection

SAW this serial number on a Northern Line carriage: 51652.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the numbers in the order they appear.
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My solution: 5 - 1 + 6 = 5 x 2

Perfect Simplicity

SAW this serial number on a Northern Line carriage yesterday: 51648.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
What makes this Tube Puzzle unusual is that not only is there a perfect solution, ie one that uses the numbers in the order they appear, but the perfect solution is also the simplest solution.
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My solution: 5 + 1 + 6 = 4 + 8

'Tube Puzzle'

SAW this serial number on a South Western train: 77712.
As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
There is a perfect solution, ie one that uses the numbers in the order they appear.
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My solution: 7 + 7 = 7 x 1 x 2

Perfect Puzzle

HERE is a carriage number from a Central Line train that makes an interesting Tube Puzzle: 52648.
As usual each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation. There are perfect answers, ie ones that use the digits in sequence.
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My solution: (5 x 2) - 6 + 4 = 8

Tricky Tube Puzzle

SAW the following serial number on a Northern Line carriage this morning: 51614.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 5 x (1 + 1) = 6 + 4

Another Brain Exercise

I SAW the following serial number on a Southern train today: 73441.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 7 + 4 = (3 x 4) - 1

Brain Exercise

I RECKON keeping the brain active must help when it comes to playing chess, or at least it does no harm.

That is why on London tube trains I like to solve what I call Tube Puzzles.

One I saw today on the Northern Line looked at first glance to be easy, but proved surprisingly tricky, at least for me.

The carriage had the serial number 53576.

As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 5 + 5 = 7 + (6 - 3)

Simple Perfection

THE following serial number from a Central Line carriage makes for a Tube Puzzle with a perfect but simple solution: 91731.
As usual, each number should be used once and once only, and must be added, subtracted, multiplied or divided to make a balanced equation. A perfect solution is one that uses the digits in the order printed.
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My solution: 9 + 1 = 7 + 3 (÷ 1)

Tricky Tube Puzzle

THE serial number of a Central Line carriage I was riding in recently was 91267.
As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 9 + 6 - 1 = 2 x 7

Perfect Trinity

RETURNING by tube on the Central Line from a match a few days ago I spotted the following carriage serial number: 91273
As usual with these tube puzzles, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
What makes this special is that there are at least three perfect solutions, ie solutions that use the numbers in the order they appear.
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My solutions: 9 - 1 ( ÷ 2) = 7 - 3

9 - 1 + 2 = 7 + 3

9 - 1 + 2 - 7 = 3

New Tube Puzzle

HERE is a serial number from a Northern Line carriage: 52627.
As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.
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My solution: 5 + 6 - 2 = 2 + 7

Single-Sign Tube Puzzle

TRAVELING on the District Line, I spotted the following serial number on a carriage: 21485.
As usual, each number should be used once, and once only, and must be added, subtracted, multiplied or divided to make a balanced equation.

There is a single-sign solution, ie one that uses only one type of the four possible signs: + - x ÷.
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My solution: 2 + 8 = 1 + 4 + 5