|
Numbers |
Definition |
Sample |
| Perfect numbers |
- numbers whose divisors
add up to the number itself. (Do not consider the
number itself as one of the divisors.) |
6 = 1 + 2 + 3
so 6 is a perfect number. |
| Deficient numbers |
- numbers whose divisors
add up to a value less than the number itself.
(Do not consider the number itself as one of the
divisors.) |
9 is a deficient number.
1 + 3 = 4 |
| Abundant numbers |
- numbers whose divisors
add up to more than the number itself. (Do not
consider the number itself as one of the divisors.) |
12 is an abundant number:
1 + 2 + 3 + 4 + 6 = 16 |
|
Figurative numbers |
- numbers that represent the
number of objects needed to form geometrical objects
such as triangles, squares, pentagons, etc. |
| Triangular numbers
|
- a number
representing the number of objects that can be used to
form a triangle. |
•
1 is a triangular number
|
•
• • 3 is a triangular
number |
•
• •
• • • 6 is a triangular number |
| Square numbers
|
- a number
representing the number of objects that can be used to
form a square.
|
•
1 is a square number
|
• •
• • 4 is a square number |
• • •
• • •
• • • 9 is a square number |
