Why was the number nine?

This is because the number of Army divisions was also nine.

The center of Berlin had amassed lots of technical units and many soldiers. Those were elite German SS units. Our battalion was right opposite to the Reichstag at that time. The building was stormed by the battalion of Major Davydov from the right and by battalion of Senior Lieutenant Samsonov from the left. There were just 300 meters remaining to reach the Reichstag. But the distance was an open area fired upon from every side. Together with Alexey Berest, the officer responsible for the political training of the battalion, we sent soldiers in one attack after another, but retreated each time. Two battalions on our side were also attempting to attack the Reichstag unsuccessfully. All the same, we carried out the order to seize the Reichstag building. It was on only the fourth attempt that our battalion rushed into the Reichstag at about 6:00 p.m. on April 30. We started hand-to-hand fighting with SS soldiers and the combat lasted till late hours. By midnight, the fight was fading away. As far as I understood, Hitler's troops had descended to some underground rooms. And we had a chance to catch our breath. We organized an all-round defense. All of a sudden, two guys from the regimental reconnaissance, Sergeant Yegorov and Junior Sergeant Kantaria came up with a Victory Flag.