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Learn how to multiply and divide integers with ease, including rules for positive and negative numbers. Practice problems included for better understanding.
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Multiplying and Dividing Integers Sec 2.4 & 2.5
Multiplying Integers • Let’s multiply! • 8(3) = • 24 • What about when we have negative numbers? • -4(-8) = • Well, 4(8) = 32 as always, but what do we do about the sign? • When multiplying • The product of two integers with the same sign is positive, so… • -4(-8) = 32
Multiplying Integers • 9 * 20 = • 180 • -5 * -12 = • 60 • (-10)(-34) = • 340 • But what happens when the signs are different? • The product of two integers with different signs is negative. • (-5)(7) = • -35
Multiplying Integers • -8 * 11 = • -88 • -12 * 4 = • -48 • (-7)(9) = • -63 • (-6)(-7) = • 42
Multiplying Integers • Every month, the school loses 40 pencils. How many will it lose in a year? • Write an expression for the above problem and solve it. • There are 9 months in a school year, so • 9 * 40 pencils = 360 pencils
Dividing Integers • Division and multiplication are related. The rules for signs in integers work the same. • The quotient of two integers with different signs is negative. • Dividend ÷ Divisor = Quotient • 12 ÷ -2 = • -6 • The quotient of two integers with the same signs is positive. • (-65) ÷ (-5) = • 13
Multiplying and Dividing Integers • (-9) ÷ 3 = • -3 • (-11)(-12) • 132 • 200 ÷ - 20 = • -10 • 7 * (-3) = • -21 • (-81) ÷ (-3) = • 27