In this activity, students locate five- and six-digit numbers on a series of number lines. The endpoints of each number line are multiples of 100,000, and the space between them is partitioned into ten equal intervals. As they locate the numbers, students recognize each tick mark as a multiple of 10,000 (MP7). Later in the activity, students use a number line to name multiples of 10,000 that are near given five-digit numbers.

• Select students to explain how they identified which number line to use and where to put the dot sticker to represent each number. Highlight explanations that are based on place-value reasoning:
  • To identify the right number line, look at the digit in the hundred-thousands place. If the number didn’t have a digit there, it goes on the first number line.
  • To locate the point, look at the digit in the ten-thousands place. For 379,000, it is the 7 in the ten-thousands place, so count 7 tick marks from 300,000. The dot would be close to the eighth tick mark because 79,000 is close to 80,000.
• Briefly discuss how students identified the nearest multiple of 10,000 for 42,326 and 99,982.
• Keep the number lines displayed for the next activity.

In this activity, students identify the nearest multiples of 10,000 and 100,000 for the six-digit numbers they saw in the first activity. Students may use number lines, but they may also notice a pattern in the relationship between the numbers and the nearest multiples without using them(MP7).

• Display the blank table from the activity. Invite students to share their responses to complete the table. Discuss any disagreements.
• Encourage students to share how they identified the nearest multiples of 10,000 and 100,000.
• If no students mentioned that they examined the location of each point visually and decided the closest tick marks on the number line, ask them about it.