Problem (Page 88). In a group of nine coins, eight weigh the same ...
Problem (Page 88). In a group of nine coins, eight weigh the same ...
Problem (Page 88). In a group of nine coins, eight weigh the same ...
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3.1. ADDITION AND SUBTRACTION 29Name <strong>the</strong> three <strong>coins</strong> in <strong>the</strong> chosen <strong>group</strong> a, b, c.(3) Balance a against b.a = b =) counterfeit coin is c.a 6= b and chosen <strong>group</strong> heavier =) counterfeit coin is heavier <strong>of</strong> a and b.a 6= b and chosen <strong>group</strong> lighter =) counterfeit coin is lighter <strong>of</strong> a and b.Two models <strong>of</strong> addition:3.1. Addition and Subtraction(1) The set model – uses <strong>the</strong> union <strong>of</strong> disjoint sets.Definition (Addition <strong>of</strong> Whole Numbers). Let A and B be any two wholenumbers. If A and B are disjoint sets with a = n(A) and b = n(B), <strong>the</strong>na + b = n(A [ B).“a” and “b” are called addends or summands.Addition is called a binary operation since two numbers are combined to producea unique number.
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