All the solutions provided in McGraw Hill Math Grade 4 Answer Key PDF Chapter 4 Lesson 2 Round to Estimate Products will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 4 Answer Key Chapter 4 Lesson 2 Round to Estimate Products
Math in My World
Example 1
There are passenger trains in the world that can travel at 267 miles per hour. About how far could a train travel in 3 hours?
Estimate 3 × 267.
Round 267 to its greatest place value.
Helpful Hint
267 rounds to ________
Then use basic facts and patterns to multiply.
To which place was 267 rounded? _______
Since 267 was rounded up, the estimated product is greater than the actual product.
So, the train can travel about ___ miles in ____ hours
Answer:
Given that,
There are passenger trains in the world that can travel at 267 miles per hour.
The number of hours is 3.
3 x 267 = 801.
267 rounded to the greatest place value is 300.
3 x 300 = 900.
Since 267 was rounded up, the estimated product is greater than the actual product.
So, the train can travel about 900 miles in 3 hours.
Example 2.
Estimate 8 × 2,496.
Round 2,496 to the thousands place value. Then multiply using basic facts and patterns.
Helpful Hint
2,496 rounds to ____
Since 2,496 was rounded down, the estimated product is less than the actual product.
So, 8 × 2,496 is about _____.
Answer:
8 x 2,496 = 19,968.
2,496 rounded to the greatest place value is 2,000.
8 x 2,000 = 16,000.
Since 2,496 was rounded down, the estimated product is less than the actual product.
So, 8 × 2,496 is about 2,000.
Example 3
Lacey’s older brother is going to a four-year college. The cost of his tuition is $8,562 each year. About how much will 4 years of college tuition cost?
Estimate 4 × $8,562.
Round to the greatest place value. Then multiply.
4 × ____ = ____
Since 8,562 was rounded _____, the estimated product is ___ than the actual product. So, tution will cost about _____.
Answer:
Given that,
The cost of his tuition is $8,562 each year.
The 4 years of college tuition cost is 4 x $8,562 = 34,248.
$8,562 rounded to the greatest place value is 9,000
4 x $9000 = $36,000.
Since 8,562 was rounded 9000, the estimated product is $36,000 than the actual product. So, tuition will cost about $36,000.
Talk Math
Which product is closer to the estimate of 1,600: 4 × 385 or 4 × 405? Explain.
Answer:
The product of 4 × 385 is 1,540.
The product of 4 × 405 is 1,620.
The 1,620 is closer to the 1,600 than 1,540.
Guided Practice
Estimate. Round to the greatest place value. Circle whether the estimate is greater than or less than the actual product.
Question 1.
greater than
less than
Answer:
Multiplication of 9 with $870 = $7,830.
9 x $870 = $7,830.
870 rounded to the greatest place value is 900.
Since $870 was rounded up, the estimated product is greater than the actual product.
9 x $900 = $8100.
Question 2.
greater than
less than
Answer:
Multiplication of 3,293 with 3 = 9,879.
3,293 x 3 = 9,879.
3,293 rounded to the greatest place value is 3,000.
Since 3,293 was rounded down, the estimated product is less than the actual product.
3 x 3,000 = 9,000
