Record a problem in which int types are multiplied and eventually become negative numbers.
int a = 60000000;
int b = 36;
When a*b you will find that it is a negative number.
This is because the value range of int (int 32) and 2 raised to the 32nd power is -2,147,483,648~2,147,483,647
If a*b exceeds this range, int will overflow, and the multiplied value will be a negative number.
For larger values, you can use long instead of int
long is Int64, the value range is -9223372036854775808~9223372036854775807
This will generally not exceed