That string of numbers wasn't handwritten but printed onto the envelope, so most people would assume it was just part of the original envelope and wouldn't connect it to the sender or the content of the letter.
Li Zhiqian also glanced at the sequence of numbers on the envelope.
Li Zhiqian said, "I've looked at this envelope for twenty-five years. I know every corner of it clearly. What about this sequence of numbers? It's just a normal envelope code."
"Li Zhiqian, for all your cleverness, look at the numbers on it—5044434433116323. They're actually eight numbers."
Li Zhiqian furrowed his brow. "What are you getting at? What tricks are you trying to play now?"
Xia Yangyang replied, "Look at the content your mother left behind. It comprises 63 characters. Now if you treat the sequence on the envelope as eight two-digit numbers, it becomes eight numbers. Use these eight numbers and correspond them to the envelope's digits to see what they mean."