mental math multiplyinglesson2.4
TRANSCRIPT
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Review
1. Is 30 a common multiple of 2 and 5? How do you know?
Find the LCM or Least Common Multiple of each set of numbers.
5, 7 4, 9 2, 6, 8
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Multiples of 10, 100, and 1000
By: Miss B
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When multiplying by multiples of 10, 100, and 1000, first multiply the non-zero digits.
Then, count the number of zeros in both factors. Write that number of zeros in the product.
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A fifth grader’s heart normally beats 90 times in 1 minute. How many times does it beat in 1 hour?
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Can the product ever contain more zeros than the number of zeros in the factors?
Yes, if the product of the non-zero digits is itself a multiple of 10, for example, 4 x 5
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80 x 90
90 x 90=
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4 x 70
5 x 900
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6,000 x 6
90 x 30
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12 x 10
30 x 40
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2 x 6000
60 x 20
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60 x 50
80 x 200
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90 x 70
2 x 5,000
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50 x ____ = 2,500
4 x _____ = 160
___ x 90 = 18,000
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___x 80= 4,000
___x 300 = 6,000
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An adults heart pumps about 5 liters of blood every minute. About how much blood is pumped in an hour?
Problem Solving