The mathematical question Huang Rong gave to his aunt

I don't know the number of things today. There are only two to three, three to five, and three to seven?

Jie Gu's C # solution: using system;
Using system. Collections. Generic;
Using system. text;

Namespace SS
...{
Class Program
...{
Static void main (string [] ARGs)
...{
Int I = 0;
While (true)
...{
I ++;
If (I % 3 = 2 & I % 5 = 3 & I % 7 = 2)
...{
Console. writeline (I );
}
}
}
}
}

 
Huang Rong solution:
Huang Rong smiled and said, "This is easy. Multiply the remainder by 70, the remainder by 21, and the remainder by fifteen. If they are not greater than one hundred and five, they are the number of answers. Otherwise, they must be reduced to one hundred and five or a multiple ." I figured it out in my heart, and it was really good. I whispered, "three or three numbers, the remainder multiplied by 70; five or five numbers ......" Huang Rong said: "You don't need to remember this. If I read a poem for you, it's easy to remember: three people walk 70 thin, five trees have one plum blossom, and the seven sons have been reunited for half a month, you will know about it in the hundreds or even five years."
Huang Rong's C # solution:
What does triplicate mean? I do the remainder of 3, but the result is incorrect.