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Estimate the product: .
Notice that 73 is near and that 46 is near
The product can be estimated by . (Recall that to multiply numbers ending in zeros, we multiply the nonzero digits and affix to this product the total number of ending zeros in the factors. See [link] for a review of this technique.)
Thus, is about 3,500. In fact, .
Estimate the product: .
Notice that 87 is close to and that 4,316 is close to
The product can be estimated by .
Thus, is about 360,000. In fact, .
Estimate the quotient: .
Notice that 153 is close to and that 17 is close to
The quotient can be estimated by .
Thus, is about 10. In fact, .
Estimate the quotient: .
Notice that 742,000 is close to , and that 2,400 is close to
The quotient can be estimated by .
Thus, is about 350. In fact, .
Estimate the quotient: .
. About 10. In fact, 10.70603675...
Estimate the sum: .
Notice that 53.82 is close to and that 41.6 is close to
The sum can be estimated by .
Thus, is about 96. In fact, .
Estimate the sum: .
. About 248. In fact, 247. We could have estimated 137.88 with 140. Then is an easy mental addition. We would conclude then that is about 250.
Estimate the product: .
Notice that 31.28 is close to and that 14.2 is close to
The product can be estimated by . ( , then affix one zero.)
Thus, is about 450. In fact, .
Estimate 21% of 5.42.
Notice that as a decimal, and that .21 is close to
Notice also that 5.42 is close to
Then, 21% of 5.42 can be estimated by .
Thus, 21% of 5.42 is about 1. In fact, 21% of 5.42 is 1.1382.
Estimate each calculation using the method of rounding. After you have made an estimate, find the exact value and compare this to the estimated result to see if your estimated value is reasonable. Results may vary.
107% of 12.6
74% of 21.93
4% of .863
( [link] ) Find the difference:
( [link] ) Convert the complex decimal to a decimal.
( [link] ) A woman 5 foot tall casts an 8-foot shadow at a particular time of the day. How tall is a tree that casts a 96-foot shadow at the same time of the day?
60 feet tall
( [link] ) 11.62 is 83% of what number?
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