Ma'anar ƙamus na hasashe lamba ita ce hadaddun lamba da za a iya rubuta ta ta sigar lamba ta gaske wadda aka ninka ta hanyar mahallin "i," inda aka bayyana "i" a matsayin tushen murabba'i na -1. Ana amfani da lambobi masu ƙima a cikin lissafi da injiniyanci don wakiltar adadi waɗanda ba za a iya bayyana su azaman lambobi na gaske ba, kamar tushen murabba'in lamba mara kyau. Yayin da ƙila ƙila ƙila ƙila ƙila ƙila ƙila ƙila ƙila lambobi ne na zahiri kuma ba su wanzu, a zahiri suna da amfani sosai wajen warware daidaito da kuma nazarin al'amuran zahiri.