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Adding and Subtracting Integers with Rules.

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CA Standard: Solving addition and Subtraction problems that arise in concrete Situations using integers. (NS 2.3) Adding and Subtracting Integers with Rules . – PowerPoint PPT presentation

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Title: Adding and Subtracting Integers with Rules.


1
Adding and Subtracting Integers with Rules.
  • CA Standard
  • Solving addition and
  • Subtraction problems
  • that arise in concrete
  • Situations using
  • integers. (NS 2.3)

2
When Adding Integers
  • If the signs are the same ( or - -)
  • Add as usual.
  • Keep sign the same.
  • A positive becomes more positive.
  • 3811
  • A negative becomes more negative.
  • -3 -9 -12

3
When Adding Integers
  • If the signs are different ( - )
  • Find the difference of the numbers.
  • (Pretend the integers are both positive and
    subtract the smaller from the bigger.)
  • -3 4
  • (4 - 3 1)
  • Determine the sign.
  • The integer with the larger absolute value
    determines the sign.
  • l -3 l 3
  • l 4 l 4
  • Answer is positive because the positive integer
    has the greater absolute value.

4
An Example or Two
  • 73
  • 10 (same sign, add as usual, keep sign)
  • -3 -10
  • -13 (same sign, add as usual, keep sign)
  • -10 3
  • -7 (find the difference 10-37, l -10 l gt l 3
    l, answer is negative)
  • 7 -3
  • 4 (find the difference 7-34, l 7 l gt l -3
    l, answer is positive)
  • -1 1
  • 0 (find the difference 1-10, zero is neither
    positive or negative

5
When Subtracting Integers
  • Change to an addition problem.
  • This changes the second number to its opposite
  • Follow addition rules.
  • -7 5
  • -7 -5 -12
  • -7 (-3)
  • -7 3 -4

6
An Example or Two
  • 7-3
  • 7 -3
  • 10 (find the difference 7-34, l 7 l gt l -3
    l, answer is positive)
  • -3 - 10
  • -3 -10
  • -13 (same sign, add as usual, keep sign)
  • -1-(-1)
  • -1 1
  • 0 (find the difference 1-10, zero is neither
    positive or negative)

7
Please write your summary.
  • Use your own words
  • Include examples
  • Include tricky things to remember
  • Explain how to check your answer
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