217
- = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( )
% < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9
( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8
9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7
8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6
7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5
6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3
NOTE TO PARENTS AND TEACHERS
Th e method of multiplication taught in this book introduces positive
and negative numbers to most children. Th e method makes positive
and negative tangible instead of an abstract idea. Positive numbers
go above when you multiply; negative numbers go below. Students
become used to the idea that when you multiply terms that are
both the same you get a positive (plus) answer. If they are diff erent
(one above and one below), you have to subtract—you get a minus
answer. Even if they don’t understand it, it still makes sense.
How do you explain positive and negative numbers? Here is how
I like to do it. To me it makes sense if you see “positive” as money
people owe you. Th at is money you have. “Negative” is money you
owe, or bills that you have to pay. Th ree bills of $2 is 3 times –2,
giving an answer of –$6. You owe $6. Mathematically it looks like
this: 3 × –2 = –6.
PLUS AND PLUS AND MMINUS INUS
NNUMBERSUMBERS
AAppendix Fppendix F
bbapp06.indd 217app 06 .indd 217 1 1/9/07 8:43:15 AM/ 9 / 07 8 : 43 : 15 AM
- = x 0 1 2 3 4 5 6 7 8 9 ( ) % < > + - = x 0 1 2 3 4 5 6 7 8 9 ( )