Please. Math Problem?
Estimate each product using rounding or compatible numbers.
1.
0.97 x 312
2.
8.02 x 70
3.
31.04 x 300
4.
0.56 x 48
5.
0.33 x 104
6.
0.83 x 12
7.
0.89 x 51
8.
4.05 x 11
9.
0.13 x 7
10.
45.1 x 5
11.
99.3 x 92
12.
47.2 x 93
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Answers & Comments
For #1, I would be inclined to replace 0.97 with (1 - 3/100) and replace 312 with 300(1+4/100)
Then (1 - 3/100)(1 + 4/100) is easily done by FOIL: 1 + 1/100 - 12/10000
Multiplying by the 300 we get:
First approximation 300(1) = 300
Second approximation 300(1+1/100) = 303
Third approximation 300(1+1/100-12/100000) = 303 - 36/100 = 302.64
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For #5 I would write 0.33 = 1/3 - 1/300 = 1/3(1 - 1/100) and 104 = 105-1 = 3(35 - 1/3)
Then the 3 and the 1/3 cancel leaving a nice FOIL:
(1 - 1/100) ( 35 - 1/3)
First approximation: (1)(35) = 35
Second approximation: 35 - 35/100-1/3 = 35 - 205/300 = 34+95/300 (about 34.3)
Third approximation: 34+95/300 + 1/300 = 34+96/300 = 34+32/100 = 34.32
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For #11, perhaps 100(1 - 7/1000) and 90(1+2/90)
FOIL gives (1 - 7/1000)(1+2/90) = 1 + 137/9000 - 14/90000
First approximation 100(90)(1) = 9000
Second approximation 9000 + 137 = 9137
Third approximation 9137 - 1.4 = 9135.6