[Emp`]

suggestion: add more than addition

switch(random(3))
{
case 0:{
	format(message, length, "+%d",a)
	solution += a
}
case 1:{
	format(message, length, "-%d",a)
	solution -= a
}
case 2:{
	format(temp, length, message)
	format(message, length, "(%s)/%d",temp,a)
	solution /= a
}
case 3:{
	format(temp, length, message)
	format(message, length, "(%s)*%d",temp,a)
	solution *= a
}
}

too lazy to think of how you would add division and multiplication correctly.

original though

edit: look again, i made a way that might work. another suggestion: try to make it a loop that just repeats based on the cvar