Dividing Rational Numbers

Student Summary

Any division problem is actually a multiplication problem:

  • 6÷2=36 \div 2 = 3 because 23=62 \boldcdot 3 = 6.
  • 6÷-2=-36 \div \text- 2 = \text-3 because -2-3=6\text-2 \boldcdot \text-3 = 6.
  • -6÷2=-3\text-6 \div 2 = \text-3 because 2-3=-62 \boldcdot \text-3 = \text-6.
  • -6÷-2=3\text-6 \div \text-2 = 3 because -23=-6\text-2 \boldcdot 3 = \text-6.

Because we know how to multiply signed numbers, that means we know how to divide them.

  • A positive number divided by a negative number always results in a negative number.
  • A negative number divided by a positive number always results in a negative number.
  • A negative number divided by a negative number always results in a positive number.

A number that can be used in place of the variable that makes the equation true is called a solution to the equation. For example, for the equation x÷-2=5x \div \text-2 = 5, the solution is -10 because it is true that -10÷-2=5\text-10 \div \text-2 = 5.

Visual / Anchor Chart

Standards

Building On
7.NS.2

7.NS.A.2

Addressing
7.NS.2.b

7.NS.A.2.b

7.NS.2.b

7.NS.A.2.b

Building Toward
7.EE.4.a

7.EE.B.4.a