Well, the Hijri date 27 Rabi Al Thani 1420 corresponds to the Gregorian date Monday, 9 August 1999. This date lies in the fourth month of the Hijri year 1420 AH, which is Rabi Al-Thani of 1420 AH. Both this Hijri and Gregorian date occur on the single day that is Monday without any doubt. The Arabic date 1420/04/27 is calculated using the Umm Al-Qura calendar and the sighting of the moon. One thing to remember is that this Arabic date may occur on different Gregorian date depending upon the region and country and obviously the moon.
If you are still not sure about the date then you can use our Arabic date converter.
The following is the conversion of the Gregorian date 9 August 1999 to its equivalent Arabic date.
The following is the conversion of the Arabic date 27 Rabi Al Thani 1420 AH to its equivalent Gregorian date.
أُو۟لَٰٓئِكَ جَزَآؤُهُم مَّغْفِرَةٌۭ مِّن رَّبِّهِمْ وَجَنَّٰتٌۭ تَجْرِى مِن تَحْتِهَا ٱلْأَنْهَٰرُ خَٰلِدِينَ فِيهَا ۚ وَنِعْمَ أَجْرُ ٱلْعَٰمِلِينَ
The reward of such will be forgiveness from their Lord, and Gardens underneath which rivers flow, wherein they will abide for ever - a bountiful reward for workers!
Surah Aal-i-Imraan(3:136)