The Number Trick—Expressions
Algebra
Name___________________
Complete the number trick by following the given directions.
Operation
Number
Pick a # 1-25
1. Do you think this number trick works for numbers other than 1-25? Try two numbers
that are negative, and two numbers that are bigger than 25 and see what you get.
2. In your groups, use the table above to develop an expression that represents the order
of operations of the number trick.
3. Simplify the expression you came up with above to show how this number trick
works:
Number Trick Expressions
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4. a) Use the following number trick to develop an expression that represents the order
of operations of the number trick.
Operation
Pick a number
Number
Expression
Multiply by –10
Add 35
Divide by –10
Subtract 14.5
Subtract your original number
b) Now simplify the last expression you came up with above.
x7

 5  x .
5. Consider the expression 4
 4

a) List the steps of the operations for this number trick.
1.
2.
3.
4.
5.
b) Use your calculator to test the number trick to be sure you get the same result no
matter what number you choose.
c) Now simplify the original expression for this problem to see how this number trick
works.
Number Trick Expressions
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6. a) Pick your favorite number. Using the following number trick,
6 x  2 
 x , what
3
number do you end up with?
b) Now simplify the original expression to see how this number trick works.
Practice Problems:
For each of the following problems, do both parts:
a) List the steps of the operations for each number trick
b) Simplify the expression.
1. 2x  6
3.
5( x  7)
3
5. 5 
6x  9
 2x
3
Number Trick Expressions
2. 9  8x
4.
 12  2 x
6
3
6.
2
( x  3)
3
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For each of the following problems, do both parts:
a) Write an expression for the given number trick.
b) Simplify the expression you came up with.
7.
Pick a number.
Add 7.
Multiply by 8.
8.
Pick a number.
Multiply by 12.
Add 15.
Divide by 3.
9.
Pick a number.
Divide by 5
Multiply by 20
10.
Pick a number.
Multiply by 20
Add 15.
3
Multiply by
5
Add 6
Number Trick Expressions
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