Posts Tagged ‘vs’

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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:

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

297411

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

 

 

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7c. Crack a Security Code for Middle School………… Yes! Really!

August 27, 2017


NB: This post has been updated twice. Disraeli said that if you want to become acquainted with a subject, write about it!!!! Mathspig’s head nearly exploded writing about this subject. But I’ve got it down to its simplest form now. One that Mathspig  finally understands.

The Complaint: Maths is really SCARY!…………….

………………………………………………………………………….

The Cause:

Some students think maths is always right or wrong and they are scared of making mistakes.

………………………………………………………………………….

The Solution:

Tackle problems that can’t be solved even by a computer. Students can only guess the answer and then test it. Anyone can make a guess. Work in groups. Every member of the group can contribute as students explore this maths.

………………………………………………………………………….

The Challenge:……………………………………………………….

Can you crack a security encryption code?….………………………………………………..

……………………..…………………….……………………………………………………………

Topics:

Prime Numbers, Really BIG numbers……………………..

…………………………………………………………………………

Prime Numbers Hide Your Secrets: SLATE

Remember the best online calculator is the WEB 2.0 Calc. NOTE: This is a secure website and you can check on its KEYCHAIN too.

You will find a fantastic list of Prime Numbers here.

Crack a Security Code WORKSHEET & ANS

Mathspig thanks Prof Kate Smith-Miles, Prof of Applied Maths, Monash University for the information about Keychains. Kate has used KEYCHAIN exercises with primary school students. They really enjoyed going home and showing their parents how to find a Keychain on the computer.