لِّيَعْلَمَ اَنْ قَدْ اَبْلَغُوْا رِسٰلٰتِ رَبِّهِمْ وَاَحَاطَ بِمَا لَدَيْهِمْ وَاَحْصٰى كُلَّ شَيْءٍ عَدَدًا ࣖ ( الجن: ٢٨ )
Liya'lama an qad ablaghoo risaalaati rabbihim wa ahaata bima ladihim wa ahsaa kulla shai'in 'adadaa (al-Jinn 72:28)
That he [i.e., Muhammad (^)] may know that they have conveyed the messages of their Lord; and He has encompassed whatever is with them and has enumerated all things in number. (Al-Jinn  : 28)
1 Mufti Taqi Usmani
so that He knows that they (angels) have conveyed the messages of their Lord. And He has encompassed all that is with them, and has comprehensive knowledge of every thing by numbers.