Slight confusion from Encounter Building text

Here, it says a single PC or 3 Victories are worth 6/8/10, etc. for the Encounter Value. When factoring in Victories increase one hero’s encounter value per 3 Victories. Is that per hero? Down in the paragraph it says with 2 victories to add another PC’s value to EV. Then, a third-level party with 3 Victories to increase by 21; 6 Victories to increase by 42. I can’t understand where the number 21 comes from at all. Seems to me that it should be EV + 10(?) For a third level PC. Or, 15 if you add the half for a Victory past 2.. Unless there’s a typo I’m missing or I’m completely misreading something. Thanks in advance!

Here, it says a single PC or 3 Victories are worth 6/8/10, etc. for the Encounter Value. When factoring in Victories increase one hero’s encounter value per 3 Victories. Is that per hero? Down in the paragraph it says with 2 victories to add another PC’s value to EV. Then, a third-level party with 3 Victories to increase by 21; 6 Victories to increase by 42. I can’t understand where the number 21 comes from at all. Seems to me that it should be EV + 10(?) For a third level PC. Or, 15 if you add the half for a Victory past 2.. Unless there’s a typo I’m missing or I’m completely misreading something. Thanks in advance!