Archive for the ‘Arithmetic’ Category
Trick 1: The Great MATHoudini
September 18, 2018
The Great MATHoudini
Requirements: 1 phone book, Great showmanship
Start by handing one member of the class a sealed envelope. It contains a name that you have seen in your mathematical mind.
All will be revealed at the end of the performance.
Ask one student to write a 3-digit number on the board.
Ask a second student to turn this number around and subtract the smallest number from the largest number.
Ask a third student to turn that number around and add the last two numbers.
Example: N1 = 371.
N2 = 173
N1 – N2 = N3 = 371 – 173 = 198
N4 = 891
N4 – N3 = 891 + 198 = 1089
Give a fourth student a phone book. Ask them to go to page 108 and count down 9 places on the first column and read out the name.
Now open the envelope.
Da! Da!
How does it work? The numbers ALWAYS add up to 1089 so you had plenty of time to check out the name in the phone book.
Source: Magic/Menatalism Tips and Tricks
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:
N1 = 3
Double: 2N1 = 6
Add 5: 2N1 + 5 = 11
x5: 5(2N1 + 5) = 55
Roll dice:
N2 = 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
You may not want Lego brick blossoms falling on your head,
but the Giant Lego Cherry Blossom tree has some awesome maths
to explore. See the tree built in fast forward below.
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:
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
