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Multiplying and dividing positive and negative numbers

Multiplying and dividing positive and negative numbers. Slideshow 5, Mr Richard Sasaki Room 307. Objectives. Multiplication and d ivision drill Learn rules for multiplying negative numbers Learn rules for dividing negative numbers Practice multiplying and dividing negative numbers.

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Multiplying and dividing positive and negative numbers

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  1. Multiplying and dividing positive and negative numbers Slideshow 5, MrRichard Sasaki Room 307

  2. Objectives • Multiplication and division drill • Learn rules for multiplying negative numbers • Learn rules for dividing negative numbers • Practice multiplying and dividing negative numbers

  3. Multiplication and Division Drill You have four minutes to complete the drill, good luck!

  4. Answers 3 12 15 5 12 46 27 24 4 24 1 16 3 0 50 3 12 32 7 40 45 40 200 6½ 36 3 4 16 14 30

  5. Answers • And here is your rating… • 1 – 4 Terrible… • 5 – 8 Disaster… • 9 – 12 Poor… • 13 – 15 So-so… • 16 – 17 Okay • 18 – 19 Good • 20 - 21 Great! • 22 - 24 Fantastic!! • 25 - 26Super Excellent!! • 27 - 30 Unbelievable!!!!

  6. Multiplying with Negative Numbers Rules for multiplying negative numbers are similar to adding or subtracting. Example Numerically, Double -4 = (-4) – 4 = (-4) x 2 Double -4. Let’s look at the number line. x2 If we double -4, we double its “size”. As it’s negative it must go further to the left. We double -4 and come to -8. This is the same as -4 and taking away another 4.

  7. Multiplying with Negative Numbers Let’s try another example. Example Calculate (-5) x 4. So here we extend -5 four times and reach -20. (-5)x 4 = -20 Basically, if we multiply a negative number by a positive, we get a negative.

  8. Multiplying with Negative Numbers How about two negatives? Example Calculate (-5) x (-6). Here we increase the weight of -5, but it goes the opposite way as it’s by a negative amount. (-5)x (-6) = 30 When we multiply a negative number by another, the answer will be positive.

  9. Dividing Negative Numbers Dividing has exactly the same rules. Examples Calculate 10 ÷ (-5). 10÷ (-5) = -2 Calculate (-18) ÷ 6. (-18)÷ 6 = -3 It doesn’t make any difference which number in the calculation is negative. If one is negative, the answer will be negative.

  10. Dividing Negative Numbers Like multiplication, if we divide a negative number by another, our result is positive. Examples Try the worksheets! Calculate (-60) ÷ (-6). (-60)÷(-6) 10 = Calculate (-5) x 8 ÷ (-2) (-5)x 8 ÷ (-2) = (-40)÷(-2) = 20

  11. Answers - Easy -15 -3 -36 -3 -10 -5 25 -36 21 -4 -10 -90,000 Yen 72

  12. Answers - Medium -60 3 -2 -3 -4 -1 -6 -8 -4 -2 1 -3 -6 -9 -12 -121 -8 -16 -4 -12 -4 1 degrees 1 0.25

  13. Answers - Hard 8 -53m -24 108 -38m 12 2 16 -0.5 -64

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