A basic lesson on multiplying integers for pre-algebra or 7th grade math. I explain where we get the various rules for the SIGNS in integer multiplication, and give examples.
For example, a positive times a negative integer can be modeled with counters. 4 x (-6) would be four groups of six negatives. The answer is negative (-24).
A positive times a negative can be "turned around" because multiplication is commutative, so it also gives a negative answer.
I present the situation with negative times a negative with a PATTERN. If we follow the pattern in a logical manner, we find that a negative times a negative MUST be positive.
In the end, we look at multiplying several integers plus powers with negative bases, such as (-2)^5 or (-10)^8, and notice that when the exponent is ODD, the answer is negative, and when the exponent is EVEN, the answer is positive.
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Learn more pre-algebra with Math Mammoth Grade 7 Curriculum at http://www.mathmammoth.com/complete/grade_7.php - available as an instant download and as printed copies. Check out the free samples also!
Tagged under: Integer,Mathematics (Field Of Study),Multiplication,Exponentiation (Literature Subject),multiplying integers,rules,Negative Number,negative times negative,positive,negative,multiplication integers
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