Archive for the ‘The Teacher Goes Bananas’ Category


Trick 3: Maths Swami Knows Your Age and Foot Size

July 9, 2018

Maths Swami 1: A Magic No.

Maths Swami 2: I Know Your Birthday

Requirements: Calculator and spooky demeanor

Imagine your birthday was 24 September 1973.

Written as an American date (not UK or Australia) this would be:


Give the calculator to a student:

Take birthday month and add 18:

9 + 18 = 27

x 25

27 x 25 = 675

– 333

675 – 333 = 342

x 8

342 x 8 = 2736

– 554

2736 – 554 = 2182

Divide by 2

2182/2 = 1091

Add day of birthday date

1091 + 24 = 1115


1115 x 5 = 5575

+ 692

5575 + 692 = 6267

x 20

6267 x 20 = 125340

Add the last two digits only of your birth year

125340 + 73 = 125413

– 32940

125413 – 32940 = 92473 = 9-24-73

Yes! Yes!

Hint: It probably would be easier to ask them for their birthday. Ha! But Maths Swami’s are mysterious beings.

You will find a video link on Youtube


Trick 4: How to be a Mathematical Clairvoyant

June 22, 2018

How to be a Mathematical Clairvoyant

Requirements: Spooky music and spooky look.

You will find some spooky music here.

Tell your students you will beat them  adding up 5 x 5 digit numbers in your head when they are using calculators.


1. Ask a student to write down 2 x 5-digit numbers on the board.

2. You rapidly write a 5-digit number underneath.

3. Ask another student to write another 5-digit number.

4. You write another 5-digit number quickly.

5. You have 5 by 5 digit numbers. Say ‘Go’. You instantly write down the answer.

Stand back.

This is how it works:

N1 = 97413

N2 = 28619

N3 = 71380  (Each digit in N3 that you write down must add up to 9 with digits in No. above)

N4 = 64231

N5 = 35768  (Once again each digit in N5 must add up to 9 with digits above)

Now you will instantly write down the sum of these five numbers as


Da! DA!

The trick is to subtract 2 from N1 and put it in front:

N1 = 97413

N1 -2 = 97411

Sum of 5 numbers = 297411

This is why it works:

Hint: When you get your students to add up the five 5-digit numbers on a calculator you will beat them, but they will also get many different answers as a number of students will key incorrect numbers.

Magic Chat




Square Root. It’s a Tree!

May 20, 2018

Just found this on Twitter! Had to share it.

If an IMAGINARY NUMBER screams alone in a forest can you imagine that you can hear it? Ha!


Trick 8: Spooky Maths Magic

May 4, 2018

Spooky Maths Magic

Requirements; Smart board/data projector.

 This is mental maths, but not hard maths. You can play this video by Marco Frezza  directly to the class.

It may not work on everybody, but it would be very interesting to see how many students are fooled by this spooky magic man.


Trick 9: Coin Trick. How to throw 10 HEADS in a row!!!!

April 30, 2018

Requirements: A coin for each student & smart board or data projector.

First ask your students to toss a coin 10 times each.

Ask each student how many heads in a row they threw.

Now ask students ‘Do you think it is possible to throw 10 heads in a row?

It can be done. Here is how you do it.

Derren Brown is a UK mentalist, magician, hypnotist and maths guru. He’s awesome. He shows audiences how a lack of understanding maths, especially probability, leads to misinterpreting the facts.

Now play this video to the students:


Trick 10: A Foolproof Gambling System

April 23, 2018

Math Mentalist Devises Foolproof Gambling System

Requirements: Smart board/Data Projector

or Chalk & Talk

This is the most awesome way to introduce probability.

Mentalist Derren Brown devises a foolproof gambling system. He sends a girl , Kadisha, the number of a winning horse in race to be run the next day. It wins. He sends her the winning horse and race number 4 more times. She ends up with winnings close to £ 1000 before the final race. Derren convinces her to borrow money for the last bet. She does. She places £4,000 on a horse. Did it win?????

Watch Part 5 of The System



If you are not convinced Derren Brown can come up with a foolproof system for horse race tipping, let me explain The System. He took 7,776 e-mail addresses, divided them into 6 equal groups and sent each group a different number for a horse in a 6 horse race to be run the next day. Naturally, one group of 1296 had been given the winning horse number.  This group was divided into 6 again and given the number of the ‘winning’ in a six horse race the next day and so on.

Race 1: 7776

Race 2: 1296

Race 3: 216

Race 4: 36

Race 5: 6

Out of 7776 punters, only one punter was given in advance five horse race winners in a row. Was it Kadisha. You will have to watch the Youtube above.

You can watch THE SYSTEM in full here. It takes 47 mins.


April Fool Maths Test

March 23, 2017

Tell your year 8 or 9 students this test is designed to test their ability to concentrate and use logic while doing a challenging test under pressure.

Tell students to circle the ‘correct’ answer. Then wait to see how long it takes them to think you have totally lost the plot! You can make copies of the test using the PDF links below. You can put the answers up later on the smart board.

Mathspig April Fools Maths Test 1

Mathspig April Fools Maths Test 2

Mathspig April Fools Maths Test ANSWER