The Prophet ﷺ used to say on the day of the breaking of the fast seven takbirs in the first rak'ah and then recite the Qur'an, and utter the takbir (Allah is most great). Then he would stand, and utter the takbir four times. Thereafter he would recite the Qur'an and bow. Abu Dawud said: This has been narrated by Waki' and Ibn al-Mubarak. Their version goes: "Seven (in the first rak'ah) and five (in the second)."
أَنَّ النَّبِيَّ ﷺ كَانَ يُكَبِّرُ فِي الْفِطْرِ فِي الأُولَى سَبْعًا ثُمَّ يَقْرَأُ ثُمَّ يُكَبِّرُ ثُمَّ يَقُومُ فَيُكَبِّرُ أَرْبَعًا ثُمَّ يَقْرَأُ ثُمَّ يَرْكَعُ