September 18, 2013
1-1 Estimating with Whole Numbers
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September 18, 2013
Estimate
Close to the exact answer but are usually easier and faster to find.
When you are estimating, you can round the numbers in the problem to compatible numbers.
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September 18, 2013
Compatible numbers
Close to the numbers in the problem, and they can help you do math mentally.
Example: 120 + 65
compatible numbers may be 120 + 60 marani
September 18, 2013
Estimating a sum or difference by rounding
What language in the answer tells you that it is an estimate?
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September 18, 2013
Independent Practice
Directions: Estimate each sum or difference by rounding to the place value indicated.
1.) 12,345 + 62,167; ten thousands
2.) 4,983 - 2,447; thousands
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September 18, 2013
Underestimate
An estimate that is less than the exact answer.
Can you think of a time when it would be appropriate to underestimate something?
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September 18, 2013
Overestimate
An estimate that is greater than the exact answer.
When would it be a good idea to overestimate something?
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September 18, 2013
Estimating a product by rounding
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September 18, 2013
Independent Practice
Don't forget
RUCO!
Chelsea is planning the annual softball banquet for the 8 teams in the region. Each team has 18 members. Estimate how many plates she will need to buy if all the members attend.
STOP and THINK. Would it be better to overestimate or underestimate in this situation?
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September 18, 2013
Estimating a quotient by using compatible numbers
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September 18, 2013
Independent Practice
Mr. Dehmel will drive 243 miles to the fair at 65 mi/hr. About how long will his trip take?
STOP and THINK. Would it be better to overestimate or underestimate in this situation?
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September 18, 2013
Think and Discuss
1.) Suppose you are buying items for a party and you have $50.
Would it be better to overestimate or underestimate the cost of the items? Why?
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September 18, 2013
Think and Discuss
2.) Suppose your car can travel between 20 and 25 miles on a gallon of gas.
You want to go on a 100-mile trip. Would it be better to overestimate or underestimate the number of miles per gallon your car can travel?
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September 18, 2013
Extra Practice
1.) 4,689 + 2,469; thousands
2.) 50,498- 35,798; ten thousands
3.) Natalie's family is having a picnic at an amusement park. The park is 153 miles from Natalie's house. If the family drives 55 mi/h, about how long will it take them to get to the park? marani