Estimate Sums and Differences

Estimate Sums and Differences

I can estimate sums and differences.

What does the term sum and difference mean?

• Sum means addition.

• Difference means subtraction.

• An estimate is a number that is close to the exact number.

How do I estimate again Ms. Coleman? I have forgotten!

42+38+54

1. Find the greatest place value of each number. Then add. The greatest place value is in the tens place.

2. Round each number to the nearest ten.

42 rounds to 40 beacuse 2 is less than 5.

38 rounds to 40 because 8 is greater than 5.

54 rounds to 50 because 4 is less than 5.

3. Add the numbers together.

Multiple Choice

Estimate the sum.

42+38+54

• 140

• 150

• 130

• 120

Example 2

Polk Elementary School has 413 students. Grant Elementary School has 278 students. About how many more students attend Polk Elementary School than Grant Elementary School?

1. Decide if you need an exact answer or an estimate.

2. Round each number to the greatest place value.

3. Decide if you need to add or subtract.

Now solve the problem.

Polk Elementary School has 413 students. Grant Elementary School has 278 students. About how many more students attend Polk Elementary School than Grant Elementary School?

Open Ended

Polk Elementary School has 413 students. Grant Elementary School has 278 students. About how many more students attend Polk Elementary School than Grant Elementary School?

Practice

Now we will go through some examples to see how well you remember.

Multiple Choice

Which shows the best way to estimate the sum?

82+59+25

• 80+50+30

• 60+60+60

• 70+50+20

• 80+60+30

Multiple Choice

Which is the best estimate of the sum?

184+245

• 300

• 400

• 600

• 750

Multiple Choice

Which shows the best way to estimate the difference?

613-178

• 500-200

• 600-100

• 500-200

• 600-200

Multiple Choice

Which is the best estimate of the difference?

404-159

• 50

• 100

• 200

• 400

Multiple Choice

A farmer planted 83 tomato seeds and 76 pumpkin seeds. Which is the best estimate of the number of seeds the farmer planted in all?

• 160

• 200

• 260

• 300

Multiple Choice

Ms. Jenkins spent $94 on a chair and $185 on a table. About how much more did the table cost than the chair?

• $50

• $100

• $150

• $200

Multiple Choice

John is reading a book with 332 pages. He has read 128 pages. Which can you use to check if the answer is reasonable?

• 300+100

• 300-200

• 300-100

• 400-100

Multiple Choice

An amusement park had 376 visitors in the morning. The park had another 145 visitors in the evening. About how many visitors did the park have that day?

• 200

• 300

• 400

• 500

Multiple Choice

Which shows the best way to estimate the difference?

613-178

• 500-200

• 600-100

• 500-200

• 600-200