Multiplication of signed numbers

Use the following rules for multiplying integers.

Multipliying Integers with the Same Signs |
The product of two integers with the same sign is positive. |

Multiplying Integers with Different Signs |
The product of two integers with different signs is negative. |

Find the products:

**a. 16·(-2)**
The two integers have different signs.
Their product is negative.
16 · (-2) = -32 |
**b. (-30)·(-5)**
The two integers have the same sign.
Their product is positive.
(-30) · (-5) = 150 |

** Rules of signs **

( + ) x ( + ) = ( + )
( + ) x ( - ) = ( - )

( - ) x ( - ) = ( + ) ( - ) x ( + ) = ( - )

In finding the product of more than two numbers, you must remember that we operate on only two numbers at a time. So we start by finding the product of any two and continue until we have used all the factors.

(+2)x(-3)x(+4)=(-6)x(+4)=-24

An easy way to find the sign of the product is to count the number of minus signs. An even number of minus signs will produce a positive product.

Note: The multiplication sign can be omited: (+3)x(-7) = (+3)(-7) = (-21)