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SLIDE SHOW INSTRUCTIONS This presentation is completely under your control. This lesson will show only one step at a time, to see the next step you must press a key. (Actual names written on a key are in green) •TO STOP THE SLIDE SHOW: press ‘escape’ (Esc, top left of keyboard) •TO MOVE FORWARD: press the “spacebar” or Enter (PageDn, , , also work) •TO MOVE BACKWARD: press the key (PageUp, or also work) Sign Rules for Addition If the terms have the same sign (both positive or both negative): Add them & keep the sign If the terms have different signs (one positive and one negative): Subtract them (big minus small) & keep the sign of the big number Same Signs: Add & keep the sign Combine -4 and -5 = -9 1. Add the numbers: 2. keep the negative 4+5=9 Combine 6 and 8 = 14 Note: Numbers that have no sign in front (on their left) are “understood” to be positive 1. Add the numbers: 2. keep the positive 6 + 8 = 14 Different Signs: Subtract & keep the sign of the bigger number Combine -3 and 7 = 4 2. keep the sign of the bigger number 1. Subtract the numbers: ( +7 is bigger than -3) 7-3=4 (Big - small: 7 is bigger than 3) Combine -10 and 7 1. Subtract the numbers: 10 - 7 = 3 (Big - small: 10 is bigger than 7) = -3 2. keep the sign of the bigger number ( -10 is bigger than +7) Sign Rules for Multiplication Count the number of negative (minus) signs in the problem If it has an odd number of negatives: The answer will be negative If it has an even number of negatives: The answer will be positive Odd number of negatives: Answers are negative Combine -4(-5)(2)(-1) = -40 2. Answer is negative 1. Count negatives: -4(-5)(2)(-1) (3 negatives): 3 is an ODD number Combine -3(-4)(-7) -14(-1) =-6 2. Answer is negative 1. Count negatives: -3(-4)(-7) -14(-1) (5 negatives): 5 is an ODD number Even number of negatives: Answers are positive Combine 4(-5)(-3) = 60 2. Answer is positive 1. Count negatives: 4(-5)(-3) (2 negatives): 2 is an EVEN number Combine -5(2)(-6) -4(-1) = 15 2. Answer is positive 1. Count negatives: -5(2)(-6) -4(-1) (4 negatives): 4 is an EVEN number Practice Problems: (Hit enter to see the answers) 1) (-6)(7) 5) - 5(-1)(-2) (-3)(4) 2) 5(-9)(-2) 6) -(-2)(8) 3) -(-3)(-10) 7) (4)(-1)(1)(-1)(-8) 4) -(-8)(-6)(-2) (-2) 8) (-11)(-12) Answers: 1) -42 2) 90 3) -30 4) -48 5) 5/6 6) 16 7) -32 8) 132 End of Tutorial Go to www.greenebox.com for more great math tutorials for your home computer Questions? send e-mail to: [email protected]