This lesson focuses on forming 3-digit address numbers to meet specific requirements. Careful reading of information and understanding of mathematical language are important to finding appropriate solutions. Using the problem-solving strategies of looking for patterns and establishing an organized list will aid students in finding all the possible solution sets.

### Learning Objectives

 Students will: experiment with numbers to find all possible ways to add three different digits to obtain a given sum (for example, 12) explore the ways three digits can be placed together to form different three-digit numbers greater than a given number (for example, 480)

### Assessment Options

1. Collect students' Create an Address Number activity sheets to verify if they found all 24 different address numbers. The solutions are as follows:
 507 570 534 543 516 561 624 642 615 651 723 732 714 741 705 750 813 831 804 840 912 921 930 903

### Extensions

 How many address numbers can be formed if the problem is the same except that the three digits need not be different? [Six more addresses can be formed: 822, 660, 606, 633, 552, 525.] How many address numbers can be formed if the problem is the same except that the number need not be greater than 480? [54 more addresses can be found (30 more than the original answer) if the digits must be different; 66 if the digits can be the same.]

### NCTM Standards and Expectations

 Number & Operations 3-5Understand the place-value structure of the base-ten number system and be able to represent and compare whole numbers and decimals. Develop fluency with basic number combinations for multiplication and division and use these combinations to mentally compute related problems, such as 3050.

### References

 Cook, Marcy. "IDEAS: Possible Solution Sets" The Arithmetic Teacher Vol.36, No.5 (January, 1989) pp. 19 -24.

1 period

### NCTM Resources

Principles and Standards for School Mathematics

 More and Better Mathematics for All Students
 © 2000 National Council of Teachers of Mathematics Use of this Web site constitutes acceptance of the Terms of Use The National Council of Teachers of Mathematics is a public voice of mathematics education, providing vision, leadership, and professional development to support teachers in ensuring mathematics learning of the highest quality for all students. The views expressed or implied, unless otherwise noted, should not be interpreted as official positions of the Council.