Automorphic Number Calculator

Enter a number to check if it's automorphic, or generate all automorphic numbers in a range.

Automorphic Number Check or Generate

What Is an Automorphic Number?

An automorphic number is a number whose powers end in the same digits as the number itself. In other words, if a number \( n \), when raised to any power, retains its own digits as the ending digits of the result, then \( n \) is an automorphic number. Automorphic numbers are categorized by the degree of the power:

  • 2nd-Degree Automorphic Numbers: A number whose square ends with the number itself.
  • 3nd-Degree Automorphic Numbers: A number whose cube ends with the number itself.
  • 4nd-Degree Automorphic Numbers: A number whose 4th power ends with the number itself.
  • And so on…

For example: A number might not be a 2nd-degree automorphic number but could still qualify for higher degrees. Some numbers, like 5, are automorphic across multiple degrees (e.g., 2nd, 3rd, 4th, etc.).

How to Determine If a Number Is Automorphic?

  1. Calculate the Power: Raise the number to the power (2nd, 3rd, 4th, up to 5th degree).
  2. Check the Ending: Verify if the ending digits of the result match the original number. If they match, the number is automorphic for that degree.

Examples

Example 1: Is 5 a 2nd-Degree Automorphic Number?

Solution:

Square Calculation: \( 5^2 = 25 \)

Ending Check: The last digit of 25 is 5, which matches the original number.

Result: 5 is an automorphic number.

Example 2: Is 4 an Automorphic Number? If Yes, Which Degree?

Solution:

Square Calculation: \( 4^2 = 16 \)

Ending Check: The last digit of 16 is 6, which does not match 4.

Cube Calculation: \( 4^3 = 64 \)

Ending Check: The last digit of 64 is 4, which matches the original number.

Result: 4 is a 3rd-degree automorphic number.

Example 3: Is 25 a 2nd-Degree Automorphic Number?

Solution:

Square Calculation: \( 25^2 = 625 \)

Ending Check: The last two digits of 625 are 25, matching the original number.

Result: 25 is an automorphic number.

Example 4: Is 12 a 2nd-Degree Automorphic Number?

Solution:

Square Calculation: \( 12^2 = 144 \)

Ending Check: The last two digits of 144 are 44, which do not match 12.

Result: 12 is not a 2nd-degree automorphic number.