س د سs-d-s
— this root is the origin of the number six, and «سِتَّةٌsittah» is formed from it (the dāl changed to tāʾ and assimilated).
سُدُسٌsudus (noun, ism dhāt): a sixth part. ﴿فَلِكُلِّ وَاحِدٍ مِّنْهُمَا السُّدُسُ﴾ (An-Nisāʾ 4:12)
سَادِسٌsādis: sixth. ﴿وَيَقُوْلُوْنَ خَمْسَةٌ سَادِسُهُمْ كَلْبُهُمْ﴾ (Al-Kahf 18:22)
سِدْسٌsids pl. اَسْدَاسٌasdās.This root occurs 5 times in the Quran.