(ن) حَسَبَ يَحْسُبُ حِسَابًا وَحُسْبَانًاḥasaba yaḥsubu ḥisāban wa-ḥusbānan: to count, to enumerate, i.e. to keep account and to reckon.
(س، ح) حَسِبَ يَحْسَبُḥasiba yaḥsabu / يَحْسِبُ حِسْبَانًاyaḥsibu ḥisbānan: to think, to suppose. ﴿اَحَسِبَ النَّاسُ اَنْ يُّتْرَكُوْٓا﴾ (Al-ʿAnkabūt 29:2)
حِسَابٌḥisāb: reckoning, account. ﴿اِنَّ اللّٰهَ سَرِيْعُ الْحِسَابِ﴾ (Āl ʿImrān 3:199)
حَاسِبٌḥāsib (active participle, ism fāʿil): one who keeps account. ﴿وَكَفٰى بِنَا حٰسِبِيْنَ﴾ (Al-Anbiyāʾ 21:47)
حَسِيْبٌḥasīb (on the pattern of فَعِيْلٌfaʿīl): one who reckons always and in every circumstance. ﴿وَكَفٰى بِاللّٰهِ حَسِيْبًا﴾ (An-Nisāʾ 4:6)
حُسْبَانٌḥusbān (intensive form on the pattern of فُعْلَانٌfuʿlān): (1) a reckoning without limit, an exact reckoning. ﴿اَلشَّمْسُ وَالْقَمَرُ بِحُسْبَانٍ﴾ (Ar-Raḥmān 55:5); (2) a severe seizing, calamity. ﴿وَيُرْسِلَ عَلَيْهَا حُسْبَانًا مِّنَ السَّمَآءِ﴾ (Al-Kahf 18:40)
حَسْبُḥasbu (verbal noun used as a noun, ism fiʿl): complete in the reckoning, i.e. sufficient. ﴿حَسْبُنَا اللّٰهُ وَنِعْمَ الْوَكِيْلُ﴾ (Āl ʿImrān 3:173)
Form III (mufāʿalah) حَاسَبَ يُحَاسِبُ مُحَاسَبَةً وَحِسَابًاḥāsaba yuḥāsibu muḥāsabatan wa-ḥisāban: to demand an account of something from someone, to call to account. ﴿فَسَوْفَ يُحَاسَبُ حِسَابًا يَّسِيْرًا﴾ (Al-Inshiqāq 84:8)
Form VIII (iftiʿāl) اِحْتَسَبَ يَحْتَسِبُ اِحْتِسَابًاiḥtasaba yaḥtasibu iḥtisāban: (1) to demand an account with care (2) to consider with care. ﴿وَيَرْزُقْهُ مِنْ حَيْثُ لَا يَحْتَسِبُ﴾ (Aṭ-Ṭalāq 65:3)