THOANS

1
THOANS!!
Think OF A Number
HKIS 2004
2

• Think of a number

X

• Add 3

X 3

• Double the answer

2(X 3)

• Add the first number you thought of

2(X 3) X
2(X 3) X 3

• Divide by 3

• Subtract 2

2(X 3) X 3
-2
What do you notice?
3
2(X 3) X 3
-2
2X 6X 3
-2
3X 6 3
-2
X 2
-2
X

• The number you thought of!!

4

• Think of a number

• Add the next higher number

• Add 9

• Divide by 2

• Subtract the original number

• What do you notice?

5

• Think of a number

X

• Add the next higher number

X X 1
2X 1 9

• Add 9

X 5

• Divide by 2

• Subtract the original number

X 5 - X
5

• What do you notice?

6
Birthdays

• Multiply the number of the day of your birth by
  100

• Add the number of the month

• Double your answer

• Add 8

7

• Multiply by 5

• Add 4

• Multiply by 10

• Add 4

• Add your age

• Subtract 444

What do you notice?
8
Birthdays

• Multiply the number of the day of your birth by
  100

100x

• Add the number of the month

100x y

• Double your answer

2(100x y)

• Add 8

2(100x y) 8
9
5(2(100xy)8)

• Multiply by 5

5(2(100xy)8)4

• Add 4

• Multiply by 10

10(5(2(100xy)8)4)
10(5(2(100xy)8)4) 4

• Add 4

• Add your age

10(5(2(100xy)8)4) 4 z

• Subtract 444

10(5(2(100xy)8)4) 4 z - 444
10
10(5(2(100xy)8)4) 4 z - 444
10(5(200x2y8)4) 4 z - 444
10(1000x10y40)4) 4 z - 444
10(1000x10y44) 4 z - 444
10000x100y440 4 z - 444
10000x100y444 z - 444
10000x100y z
11
Chocoholics!

• How many times per week would you like to have
  chocolate?

• Double this number

• Add 5

• Multiply it by 50

12

• If you already have had a birthday this year, add
  1754, if not add 1753

• Now subtract the four digit year that you were
  born. You should have a three digit number.

• What do you notice about your new number? Why
  does it work?