PPSC Past Paper Assistant Planning & Development 2019 Solved MCQs, Maths MCQs, PPSC Solved Past Papers MCQsWhich one of the following is not a prime number? Posted on April 21, 2021 by Rana TahirA. 11 B. 61 C. 91 D. 31Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on WhatsApp (Opens in new window)Click to share on Pinterest (Opens in new window)Click to share on LinkedIn (Opens in new window)