Note 5 — BOOK I.
Reading edition
This should be (23) a × a, but the sign × is unnecessary here. It is used with numbers, as in 2 × 7, to prevent confounding this, which is 14, with 27.
Reading edition
This should be (23) a × a, but the sign × is unnecessary here. It is used with numbers, as in 2 × 7, to prevent confounding this, which is 14, with 27.