﴿ لَّقَدْ أَحْصَىٰهُمْ وَعَدَّهُمْ عَدًّۭا ﴾

“indeed, He has full cognizance of them, and has numbered them with [unfailing] numbering;”

Verily He knows their number and has counted them precisely and therefore the knowledge of their total number does not elude Him not even the knowledge of one of them.