Squares Ending in 5 Occurrences of 2-Digit Pattern/Mistake

Source Work

1986: David Wells: Curious and Interesting Numbers:

The Dictionary

$21$

Mistake

If a square ends in the pattern $xyxyxyxyxy$, then $xy$ is either $21$, $61$ or $84$.

Correction

Also there are $29$ and $69$.

In David Wells: Curious and Interesting Numbers (2nd ed.), this has been corrected.

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $21$