Kaprekar's Process for 2-Digit Numbers/Mistake

Source Work

1986: David Wells: Curious and Interesting Numbers:

The Dictionary

$63$

1997: David Wells: Curious and Interesting Numbers (2nd ed.):

The Dictionary

$63$

Mistake

Kaprekar's process for $2$-digit numbers leads to the cycle $63 - 27 - 45 - 9 - 81 \ldots$

The statement needs to specify that the $2$-digit numbers do not include repdigit numbers, as for example:

$\map K {11} = 11 - 11 = 0$

trivially.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $63$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $63$