Divisibility of Elements of Pythagorean Triple by 7/Mistake

Source Work

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

The Dictionary

$7$

Mistake

If $a$, $b$ are the shorter sides of a Pythagorean triangle, then $7$ divides one of $a$, $b$, $a - b$ or $a - b$.

Correction

An obvious misprint for:

If $a$, $b$ are the shorter sides of a Pythagorean triangle, then $7$ divides one of $a$, $b$, $a - b$ or $a + b$.

It can also be argued that it ought to say:

... then $7$ divides at least one of ...

Interestingly and oddly, this is correct in the first edition of Curious and Interesting Numbers of $1986$.

Sources

• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $7$