Digit Time

Activity One

Compact numeral cards help students understand the way multidigit numbers are composed. They reinforce the idea of zero as a place holder. However, the ability to use compact numeral cards correctly is not a sufficient indicator of place value understanding.
You can develop students’ familiarity with reading and writing a three-digit number by having them collectively try to find all the numbers that Caleb could make. This might be further expanded with problems such as:
“Which number is the smallest/greatest? How do you know?”
“Which number is closest to 600?”
“Can Caleb make the number that is 110 less than 469?”

Activity Two

Converting compact numerals to expanded numerals is made much easier by using the cards. This should be a temporary aid only as students should perform this renaming task mentally. Expanding numerals is excellent preparation for performing operations on multidigit whole numbers. As an additional exercise, provide tasks where students are required to write the compact numeral for an expanded set of cards. For example:

Activity Three

Zapping the digits is a difficult application of place value. Students who are familiar with compact numeral cards may see a connection between zapping a digit and removing a compact numeral card. For example:

A more difficult application of this idea is to suggest that the calculator “change its …”. For example, students might put 762 in the window and be told to change the
display to 642, using the smallest number of key presses. Pressing on/c is not
permitted.

Answers to Activities

Activity One
859, 854, 879, 874, 839,
359, 354, 379, 374, 339, 334
If the students use zero, they may also get:
804, 870, 830, 850, 809,
304, 370, 330, 350, 309
Activity Two
1. 742 = 700 + 40 + 2
2. 999 = 900 + 90 + 9
3. 508 = 500 + 8
4. 444 = 400 + 40 + 4
5. 630 = 600 + 30
Activity Three
1. One way to do this is to subtract 70.
2. Subtract 500.
3. Subtract 4.
4. Subtract 10.
5. Subtract 200 and then 90 or subtract 290