The reason why college students can't solve this problem of primary school students is because they have never found a breakthrough.

The breakthrough of this problem is divisor, which should be 23.

Because for the first time, his injury 69, 69 was 3×23. So the first number is 23 and the first number above is 3.

Then think about how many times 23 is greater than 100, and the single digit is 4. With this idea, the topic was worked out.