## Archive for the ‘Arithmetic’ Category

## Trick 1: The Great MATHoudini

September 18, 2018## Trick 2: The Math Teacher Knows

August 4, 2018……………………………………………………………………………………

# The Math Teacher Knows Everything

### Requirements: 1 die, a fanfare would be nice.

### You will find a fanfare here.

### Ask a student to roll the die, double the number and add 5. He can show the class the number, but not you.

### Ask the student to multiply this number by 5.

### Ask the student to roll the die again and add this number to the total.

### Now you can tell them the numbers they rolled.

### Example:

### N_{1} = 3

### Double: 2N_{1 }= 6

### Add 5: 2N_{1} + 5 = 11

### x5: 5(2N_{1} + 5) = 55

### Roll dice:

### N_{2} = 4

### Add 4:

### 55 + 4 = 59

### The Math Teacher Knows:

### Secretly subtracts 25 from this number:

### 59 – 25 = 34

### Da! Da! There are the two numbers rolled.

### Source: Magic/Menatalism Tips and Tricks

## Awesome Lego Maths and a Giant Lego Tree

July 28, 2018## 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:

### 9-24-73.

### 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

### x5

### 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.**

# Method:

### 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:

### N_{1 }= 97413

### N_{2} = 28619

### N_{3} = 71380 (Each digit in N_{3} that you write down must add up to 9 with digits in No. above)

### N_{4} = 64231

### N_{5} = 35768 (Once again each digit in N_{5} must add up to 9 with digits above)

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

### 297411

### Da! DA!

### The trick is to subtract 2 from N_{1 }and put it in front:

### N_{1 }= 97413

### N_{1 }-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

## Learning Jump Strategy from a Young Mathematician

June 8, 2018**Mathpig just learnt this from a young Mathematician age 9.**

**It is a great way to do maths because you are thinking ‘Mmmm! How can I work these numbers.’ **

**Getting maths students to think about what they are doing is so much better than just having them guess ‘ Arrrr! Whatever. Click B.’**

**More jump strategy information here.**

**This will be very useful later when it comes to a similar method used to simplify long division:**