Therefore, by subtracting 1260 (21 times 60) from 601, one is led to conclude that 660 B.C. (note that there is no such year as 0 A.D.) is the year when Jinmu was entrhroned as the first emperor.
すると21×601260よりAD601－1260BC660（西暦0年はない）が神武天皇即位年と算出される。