Addition Properties and Subtraction Rules

1
Addition Propertiesand Subtraction Rules

• What they are and how they help

2
Addition Properties

• Commutative Property - Changing the order of
  addends does not change the sum.
• Example 3 4 7 4 3 7
• Identity Property - The sum of zero and any
  number is that number.
• Example 9 0 9 0 5 5
• Associative Property - Changing the grouping of
  addends does not change the sum.
• Example (3 2) 5 12 3 (2 5) 12

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Benefits of knowing the Addition Properties

• Better fact mastery
• Memorization needs reduced.
• Increased number sense.
• Use order changes for easier groupings
  (complement numbers sums of 10 or 100)
• Short cuts in adding more than 2 numbers
• Group to allow more mental addition
• Better groundwork for algebraic concepts
• Solving for missing numbers or variables

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Subtraction Rules

• Subtraction is the inverse of addition (it
  undoes addition)
• The subtrahend is subtracted from the minuend to
  find the difference.
• When the minuend is equal to the subtrahend the
  difference is always zero.
• When zero is the subtrahend the difference is
  always equal to the minuend.

14 Minuend -8 Subtrahend 6 Difference
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How Subtraction Rules Help

• Use addition to check subtraction of larger
  numbers.
• Faster recall of subtraction facts.
• Better responses in choosing the correct
  operation in word problems.