3.1. ADDITION AND SUBTRACTION 35
Definition (Subtraction – Take-Away Approach).
Let aand bbe any whole numbers and Aand Bbe sets such that a=n(A),
b=n(B), and B✓A. Then
ab=n(AB).
“ab” is the di↵erence of aand b, “a” is the minuend, and “b” is the subtrahend.
Subtraction – the missing addend approach
Definition (Subtraction - Missing Addend Approach).
Let aand bbe any whole numbers. Then ab=cif and only if ( () )
a=b+cfor some whole number c.
This approach is useful for learning subtraction facts by relating them to addi-
tion facts via four-fact families:
