Abundant and Deficient NumbersDate: 10/14/97 at 12:28:17 From: Krysti Byers Subject: Abundant and deficient numbers I need information on what these are. I also need some information on how these are used in elementary school teaching. For example, what are they used for? Thank you! Date: 10/14/97 at 18:37:36 From: Doctor Chita Subject: Re: Abundant and deficient numbers Hi Krysti: Before defining deficient and abundant with respect to numbers, we first need to recall that the natural numbers are either prime or composite. Prime numbers are those numbers that have two unique factors: {2, 3, 5, 7, ... }. Composite numbers are made up of combinations of prime factors. The set of prime factors, or divisors of a number, determines whether a composite number is deficient, abundant, or perfect. A deficient number is a composite number in which the sum of its factors is less than the given number. For example, the number 8 has factors (divisors) of 1, 2, 4, and 8. If you disregard 8 as a factor, then the sum 1 + 2 + 4 = 7 and 7 is less than 8. Therefore, 8 is deficient. An abundant number is a composite number whose factors, without the number itself, have a sum greater than the number. For example, 12 has factors of 1, 2, 3, 4, 6, and 12. The sum 1+2+3+4+6 = 16, and 16 > 12. A perfect number is one whose factors are equal to a given number. So, 6 is perfect because 1+2+3 = 6. Identifying these interesting numbers provides motivation for students to develop their number sense while practicing their arithmetic facts. You could have students make a table listing the numbers from 1 to 100 in Column 1. In Column 2, have them write all the factors of each number, including 1 and the number. In Column 3, have them find the sum of the factors (without including the number itself). In Column 4, identify the nature of the number. Have students work together to draw conclusions from their table. What patterns do they see? How many perfect numbers are there less than 100? Are there more abundant or deficient numbers? Are square numbers perfect? What about even numbers? Odd numbers? There are many other questions you can have students think about as they explore the numbers. As they answer questions, they come to new understandings about numbers. There is also a lovely little paperback book called _A Number for Your Thoughts_ written by Stephen P. Richards and published in 1982. If you can get hold of it, in it you will find abundant, if not perfect, stories about numbers. Have fun! -Doctor Chita, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/dr.math/