An example of a rotational symmetry number is 0.
Understanding Rotational Symmetry in Numbers
Rotational symmetry in the context of numbers, often called upside-down symmetry, refers to digits or entire numbers that appear the same when rotated 180 degrees. Imagine rotating a piece of paper with the number written on it completely upside down; if the number still looks like the original, it has rotational symmetry.
According to the provided reference, certain individual digits possess this property:
- 0
- 1
- 8
These digits retain their original form when rotated 180°.
Examples of Numbers with Rotational Symmetry
Based on the definition and the provided reference, the following single digits are examples of those exhibiting rotational symmetry:
- 1
- 8
The reference specifically states: "0 , 1 , and 8 have rotational symmetry."
Digits That Change Upon Rotation
Not all digits have this symmetry. For instance, the reference notes that "6 becomes 9 and vice versa". This means 6 and 9 do not have rotational symmetry themselves, though they transform into each other when rotated. Other digits like 2, 3, 4, 5, and 7 also change their appearance or become unrecognizable symbols when rotated 180°.
Numbers Formed by Symmetric Digits
Beyond single digits, multi-digit numbers can also exhibit rotational symmetry if they are composed entirely of symmetric digits and maintain their numerical value when rotated. Examples could include:
- 11 (looks like 11 upside down)
- 88 (looks like 88 upside down)
- 101 (looks like 101 upside down)
- 181 (looks like 181 upside down)
- 808 (looks like 808 upside down)
- 818 (looks like 818 upside down)
- 888 (looks like 888 upside down)
These numbers are made using only the symmetric digits 0, 1, and 8, and when rotated 180°, they read the same number.
Summary of Symmetric Digits
Here's a quick overview of the digits discussed:
| Digit | Rotated 180° | Has Rotational Symmetry? |
|---|---|---|
| 0 | 0 | Yes |
| 1 | 1 | Yes |
| 8 | 8 | Yes |
| 6 | 9 | No |
| 9 | 6 | No |
| 2,3,4,5,7 | (Other forms) | No |
In conclusion, a simple example of a number with rotational symmetry, as directly provided by the reference, is 0. Other examples include 1 and 8.
