Lesson HOW TO multiply negatives

Source code of 'HOW TO multiply negatives'

This Lesson (HOW TO multiply negatives) was created by by ichudov(507)

: View Source, Show
About ichudov: I am not a paid tutor, I am the owner of this web site!

The rule of how to multiply negatives is simple:

<CENTER><TABLE WIDTH=50% border=1><TR><TD>To multiply a negative number by any number, take the (positive) opposite of the negative number and multiply it by the other number, and take the opposite of that</B></TD></TR></table></CENTER>

<H4>Negative by positive number</H4>

For a case where a negative number is multiplied by a positive, the rule above can be restated as: take the positive number, and the negative WITHOUT the minus sign,  multiply them and add the inus sign to the product.

Example: multiply 5 and -3.

Take 5 and -3 without the "-" sign: 5 and 3

Multiply them: 5*3 = 15.

Add the minus sign: -15.

Conclusion: <B>Product of a negative and a positive is always a negative number</B>.

<H4>Negative by negative number</H4>

When you have to multiply two negative numbers, such as (-5) * (-3), the rule above should be applied twice:

(-5)*(-3) is the opposite of 5*(-3), which is the opposite of the opposite of 5*3.

5*3 is 15

Opposite of 15 s -15.

Opposite of opposite of 15 is opposite of -15, and opposite of -15 is 15 again.

Conclusion: <B>Product of a negative multiplied by negative is always POSITIVE</B>.

Here's a handy table: sign of result when we multiply
<TABLE cellspacing=10 align=center>
  <TR><TD>Multiply:</TD><TD align=center>Positive</TD><TD align=center>Negative</TD></TR>
  <TR><TD>Positive</TD><TD align=center><FONT SIZE=+4 COLOR=red>+</FONT></TD><TD align=center><FONT SIZE=+4 COLOR=red>-</FONT></TD></TR>
  <TR><TD>Negative</TD><TD align=center><FONT SIZE=+4 COLOR=red>-</FONT></TD><TD align=center><FONT SIZE=+4 COLOR=red>+</FONT></TD></TR>
</TABLE>

Examples:

2*3=6
2*(-3) = -6
(-2)*3 = -6
(-2)*(-3) = 6