Guess my #

Number puzzles always fascinated me as a child. When I learned the algebra behind them,I liked them even more. :)

Now as a teacher, I like to start Alg/Alg II with this activity. The students are usually amazed when you first do them. Then you can draw them in so they don't mind writing and simplifying expressions because they want to know how it works. Here are some of the basic ones I started with:

Guess my Number
1. Pick a number between 1 and 100.
2. Double it
3. Add 100
4. Take half the result
5. Subtract the number you started with.

Number 2
1. Pick a number
2. Add 9
3. Multiply by 3
4. Subtract 6
5. Divide by 3
6. Subtract original number.

Number 3.
1. Pick a number.
2. Multiply it by 9
3. Subtract 18
4. Divide by 9
5. Subtract your original number.
6. Add 2




Then I have the kids write their own and show the algebra behind it. We are still at the basic stage, but I am still proud of their work during the first week of school.
(Dan Meyer has some great ones to help the kids move from completing puzzles to creating them.)

1. Pick a number
2. Multiply by 4
3. Subtract 10
4. Divide by 4
5. Add 5
6. Subtract number started with

1. Pick a number
2. Add 12
3. Multiply by 2
4. Subtract 4
5. Divide by 2
6. Subtract the number you started with

1. Pick a number
2. Subtract 3
3. Multiply by 3
4. Add 9
5. Divide by 3
6. Subtract the number you started with

1. Pick a number
2. Subtract 15
3. Divide by 5
4. Subtract 3
5. Multiply 5
6. Subtract the number you started with

1. Pick a number
2. Add 6
3. Multiply by 3
4. Subtract 3
5. Divide by 3
6. Subtract the number you started with