When it was raining overnight, Zhang Tie kept cultivating until midnight in the mountain cave. Finally, he visualized and manifested the last layer of the shell of that 7-layer gold egg with his spiritual energy and battle qi. This indicated that he had accomplished the second step of planting the gold seed rune of "King Roc Sutra". What he needed to do then was to visualize and manifest 987 special runes on the shell of the golden egg.
Zhang Tie found that the number of surge points in his body and the special runes that he needed to visualized were both 987. He knew that there must be some mysterious connection between the two aspects although he didn't know why.
If Zhang Tie couldn't understand something, he would drop it. Like the moon always being round, somethings weren't worth consideration. What is rational is actual and what is actual is rational. Therefore, Zhang Tie would not concern himself with it at all.