Grade 7
a # a21 5 a21 # a 5 1
Note that a21 5 1∙a.
7. (Distributive Law) Multiplication is distributive over addition.
a(b 1 c) 5 ab 1 ac
Note that Property 5 provides the means to subtract by defining a 2 b 5 a 1 (2b) and
Property 6 provides a means to divide by defining a 4 b 5 a ? (1∙b). The number 0 has no
multiplicative inverse, so division by 0 is undefined.