Rounding to the Nearest Thousand on a Vertical Number Line
This Grade 4 Eureka Math skill teaches students to round multi-digit numbers to the nearest thousand using a vertical number line. Students plot the given number between its two nearest thousands on the vertical line and compare its position to the midpoint (500 above the lower thousand). Numbers below the midpoint round down; numbers at or above round up. For example, 4,289 plotted between 4,000 and 5,000 is below the 4,500 midpoint, so it rounds to 4,000. This visual method from Chapter 3 of Eureka Math Grade 4 makes rounding decisions concrete.
Key Concepts
To round a number to the nearest thousand, plot it on a vertical number line. If the number is less than the midpoint, round down to the lower thousand. If the number is greater than or equal to the midpoint, round up to the upper thousand.
Common Questions
How do you use a vertical number line to round to the nearest thousand?
Draw a vertical line. Mark the lower thousand at the bottom and the upper thousand at the top. Find the midpoint (lower thousand + 500). Plot the number on the line and see whether it is above or below the midpoint.
Where does 4,289 fall on a vertical number line between 4,000 and 5,000?
4,289 is below the midpoint of 4,500. Therefore, it rounds down to 4,000.
What is the midpoint between 4,000 and 5,000?
4,000 + 500 = 4,500. Numbers at or above 4,500 round up to 5,000; numbers below round down to 4,000.
Where does 6,812 round to on a number line between 6,000 and 7,000?
The midpoint is 6,500. Since 6,812 is above 6,500, it rounds up to 7,000.
Why use a vertical number line instead of a horizontal one for rounding?
The vertical format makes it easy to see whether a number is closer to the top (upper thousand) or the bottom (lower thousand), visually reinforcing the decision to round up or down.