What is four plus six times three?

1

• What is four plus six times three?

2
Order of Operations

1. Evaluate expressions within parentheses or other
   grouping symbols.
2. Evaluate all powers.
3. Multiply and divide from left to right.
4. Add and subtract from left to right

3
What do you get if you start with 5

• Using the graphing calculator and the home
  screen.
• Start with 5.
• Multiply 6 times a starting number, then add 15,
  divide this result by 3, and then subtract your
  answer from 80.
• Start with 14.
• Multiply 6 times a starting number, then add 15,
  divide this result by 3, and then subtract your
  answer from 80.
• Start with -3
• Multiply 6 times a starting number, then add 15,
  divide this result by 3, and then subtract your
  answer from 80.

4

• Write an expression with a variable for your
  number

• On the Graphing Calculator

• x
• 6x
• 6x15
• (6x15)/3
• 80-(6x15)/3

• Select any number.
• Multiply 6 times your starting number.
• Then add 15
• Divide this result by 3
• Subtract your answer from 80.

5
Evaluating an expression on the calculator

• 5 gt x80-(6x15)/3
• Your Number gt x80-(6x15)/3
• gt means STO

6
Number Tricks

• Page 136
• Materials Needed
• Set of Algebra Tiles

7
Number Tricks

• Each person pick any number from 1 to 25.
• Add 9 to it.
• Multiply the result by 3.
• Subtract 6 from the current answer.
• Divide this answer by 3.
• Now subtract your original number.
• Compare your results.
• Will the answer be the same regardless on the
  number you begin with?

8

• Complete steps 1 to 4 in the investigation. Be
  prepared to discuss your results. Work with each
  other to complete the task on the graphing
  calculator.

9

• For step 5 build a model on your desk using the
  Evaluate an Expression Template and a set of
  algebra tiles. Each yellow tiles represents 1
  and each green rectangle represents n.
• Build a picture for each stage.
• Describe what is happening.
• Write the expression for the stage.

10

• For step 8 create your own trick that has at
  least 5 stages.
• Test it on your calculator with at least four
  different numbers to make sure all the answers
  are the same.
• When you think your trick works, test it on your
  other group members.

11
Example

• Write in words the number trick that is described
  above.
• Test the number trick to be sure you get the same
  result no matter what number you choose.
• Which operations that undo previous operations
  make this number trick work?

12

• Study Example C on page 139
• Each group will work on either problem 4, 5 or 6
  on page 140. Be prepared to present your
  solution to the problem.