Teacher2Teacher Q&A #9415

Teachers' Lounge Discussion: Integers

T2T || FAQ || Teachers' Lounge || Browse || Search || T2T Associates || About T2T

View entire discussion
[ next >>]

From: Teresa Fusco

To: Teacher2Teacher Public Discussion
Date: 2002111910:34:47
Subject: subtracting a negative (4 - - 2 = 6)

A new way I learned to "see" how subtracting a negative is adding a positive is: 4 - - 2 = 6 Draw +1 in a circle for each of the first number (or whatever sign applies to another set of numbers in your problem), so in my example you have four small circles with +1 inside. Now, you can not take away any negatives because you only have positives. However, +1 and -1 added together equal zero, so add two sets (I am going to need 2 negatives in MY problem, yo need to see how many are needed in different problems) of +1 -1 to your set of four +1's from above. Now, you have four +1's and two +1's and two -1's. If you cicle and pull out two -1's (which is subtracting 2) you are left with the four +1's and the two +1's which equals +6 which is the answer! get it?

Teacher2Teacher - T2T ®
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/