円周率 Otherwise they use the Greek π or katagana パイ

pi = 円周率(En-Shu-Ri-Tsu). 3.14 is the same. (It is odd that you write mathematical explanation in kanji. But pronounce "Than-Ten-I-Chi-Youn")

Hm… 死 seems close enough, maybe just go with that! (Just kidding, maybe a bad Idea lol… thought it was a funny coincidence tho!)