SAT Math : How to multiply negative numbers

Example Questions

Example Question #1 : How To Multiply Negative Numbers

If  is a positive number, and  is also a positive number, what is a possible value for ?

Explanation:

Because is positive,  must be negative since the product of two negative numbers is positive.

Because  is also positive, must also be negative in order to produce a prositive product.

To check you answer, you can try plugging in any negative number for .

Example Question #41 : Integers

Multiply the following negative numbers: .

Explanation:

When two negative numbers are multiplied by each other, the result is a positive number.

When a negative and a nonnegative number are multiplied with each other, the result is a negative number.

Therefore, since  and  are negative numbers, the product must be positive.

Therefore, the answer is positive .

Example Question #42 : Integers

Multiply:

Explanation:

Simplify the expression term by term.

A negative number multiplied by a negative number gives a positive number.

A negative number multiplied by a positive number gives a negative number.

Example Question #43 : Integers

Multiply:

Explanation:

Multiply the first two terms.  A negative number times another negative will result in a positive number.

Multiply 27 with negative 2.  A positive number times a negative number will result in a negative number.

Example Question #44 : Integers

Solve the following equation:

Explanation:

If there are two negative signs, then the answer will be positive. If there were only one negative sign, the answer will be negative.

Example Question #45 : Integers

Simplify the following expression:

Explanation:

Simplify the following expression:

Let's begin by expanding the inside of the parentheses.

Now, it is important to use all three negative signs. The first two will cancel out, but the third one will remain, ensuring our final answer will be negative.