$12920 ⇒ ln `V` = ln (12920) ≈ 9.467 (3sf)

Based on the given scale of the ln `V`-axis, the smallest graph paper unit is 0.01. Plus given that only an *estimate* is required, your 9.467 vs our 9.465 is really, *really* close enough so "DON'T WORRY, BE HAPPY"!