Estimate the location of 28,500 on the number line and label it with a point.
Which point—A, B, or C—could represent a number that is 10 times as much as 28,500? Explain your reasoning.
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Response shows a point to the left of A, about a third of the way or halfway between 0 and A.
Point B. Sample response: Ten times 28,500 is 285,000, which would be between the tick marks that show 200,000 and 300,000, closer to 300,000. Point A is in the 80,000s and point B is in the 300,000s.
Section B Check
Section B Checkpoint
Problem 1
Write the number 436,089 in expanded form and in word form.
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Expanded form: 400,000+30,000+6,000+80+9
Word form: four hundred thirty-six thousand eighty-nine
Problem 2
Select all numbers in which the value of the 7 is 70,000.
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B, F
Problem 3
Write a number where the value of the 5 is 10 times the value of the 5 in 152,318.
Here are two numbers, each with the same digit missing in different places.
17,042
10,724
If the missing digit in both numbers is 1, which number will be greater: the first or the second?
Name all the digits from 0 to 9 that will make the second number greater. Explain how you know.
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The first number. Sample response: The first number will be 17,142 and the second number 11,724. Seventeen thousand is greater than eleven thousand.
8 and 9. Sample response: Using 8 or 9 in the second number makes 18,724 or 19,724, which is greater than a number in the 17,000s. Using 7 makes 17,724, which is still less than 17,742.
Planes are too close when their altitudes are within 1,000 feet of each other when they fly over the same area.
Jada says Planes C and E are too close.
Noah says Planes C and E are a safe-distance apart.
Use rounding to explain how both statements might be correct.
plane
altitude (feet)
A
40,990
B
39,524
C
36,138
D
40,201
E
35,472
F
30,956
Show Solution
Sample response: Jada might have thought about the actual distance between the two planes, which is only about 700 feet apart, or might have rounded to the nearest hundred (C would round to 36,100 and E to 35,500). If Noah rounded to the nearest thousand, Plane C would round to 36,000 and E would round to 35,000, which is 1,000 feet apart.
Section C Check
Section C Checkpoint
Problem 1
Write comparison statements using heights of mountain peaks in Colorado in the table.
The populations, in 2017, of the three largest cities in Wisconsin are shown.
city
population
Milwaukee
595,351
Madison
255,214
Green Bay
105,116
Was the total population of the three cities more than one million people? Explain or show your reasoning.
How much over or under one million is the total? Explain or show your reasoning.
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No. Sample response: Milwaukee had about 600,000 people. Madison had about 255,000 people. Green Bay had about 105,000 people. The sum of the three estimates is 960,000 people.
44,319 people below one million. Sample response:
The sum of populations of Milwaukee and Madison is 595,351+255,214, which is 850,565 people. Adding the population of Green Bay, 850,565+105,116 gives 955,681 people. Subtracting 955,681 people from 1,000,000 people gives 44,319 people.
The total population of the three cities is 955,681 people. I kept adding numbers to that total until reaching 1,000,000 people. I first added 40,000 people and then 4,000 people, which gives 999,681 people. Adding 319 people more gives 1,000,000 people. Then I added these numbers: 40,000+4,000+319=44,319.
Subtracting the population of Milwaukee from one million, 1,000,000−595,351 gives 404,649 people. Subtracting the population of Madison from 404,649 people gives 149,435 people. Subtracting the population of Green Bay from 149,435 people gives 44,319 people.