Hi Simon, thanks a lot. I googled a bit on this and usually log is understood as log base 10. Didn't realized that it was actually LN in the formula. I can derive the answer given in the Q&A now. Its not too clear in the readings and also in the Actuarial formula booklet on this.
Log is used to refer to both base 10 and base e. In the Actuarial Tables it is stated on page 1 of the yellow formula pages that "log" refers to base e (ie ln)