3.1. ADDITION AND SUBTRACTION
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Definition (Subtraction – Take-Away Approach).
Let a and b be any whole numbers and A and B be sets such that a = n(A),
b = n(B), and B ✓ A. Then
a
b = n(A
B).
“a b” is the di↵erence of a and b, “a” is the minuend, and “b” is the subtrahend.
Subtraction – the missing addend approach
Definition (Subtraction - Missing Addend Approach).
Let a and b be any whole numbers. Then a
a = b + c for some whole number c.
b = c if and only if ( () )
This approach is useful for learning subtraction facts by relating them to addition facts via four-fact families: