Unironically, either Assembly a domain specific language like octave.
Why assembly? It's the closest to how a computer actually functions, it hyperliteral If I say
mov $5, %rdi
mov $60, %rax
syscall
then you know for sure, the number 5 is going to be in rdi thne, the number 60 is going to be in rax. And then a syscall will happen.
The OS then takes over and reads rax, sees that 60 (which is the exit operation on linux), the exit operation is defined to have 1 argument located in rdi, so then the OS reads rdi and passes 5 as an argument to exit, exit exits the program with the same exit code as the argument in rdi, so 5 in this case.
All very mathematical.