#include
#include /*include time travel capability*/

/*declare stuff*/
int sel;
int loop;
float num1;
float num2;
float answer;

/*here is the program*/
int main()
{
loop = 0;

srand(time(NULL)); /*Putting clock into the random!*/

/*main menu*/
while (loop == 0){
printf(“Welcome to the MATHULATOR 9000n”);
printf(“You are using the worlds most advanced number calculating machinen”);
printf(“Please enter the type of calculation you would like to perform:nn”);
printf(“1. Combine two numbers… to make one bigger numbern”);
printf(“2. Remove one number from another numbern”);
printf(“3. Multiplixicaton!n”);
printf(“4. Make a number into a certain number of pilesn”);
printf(“5. Quantum calculusn”);
printf(“6. Exitnn”);
printf(“Make your selection now: “);

scanf(“%d”, &sel);

/*addition portion*/
if (sel == 1){
printf(“Enter the first number you wish to use: “);
scanf(“%f”, &num1);
printf(“Enter the second number to combine with the first: “);
scanf(“%f”, &num2);
printf(“Now Addifying!n”);
answer = num1 + num2 + (rand()%10) – (rand()%10);
if (answer > 1000) answer = answer + (rand()%100) – (rand()%100);
/*answer output*/
if (answer > 0 && answer < 10000) printf("Those two numbers make something near %.0f… or something like thatn", answer);
if (answer 9999) printf(“The answer is: a lot, like more than four digits or somethingn”);
if (answer > 1000000) printf(“what the hell is wrong with you? trying to make me add numbers like that!n”);
if (answer == 1337) printf(“I hate that number!n”);
printf(“nnn”);
}

/*subtraction portion*/
if (sel == 2){
printf(“Enter the first number you wish to use: “);
scanf(“%f”, &num1);
printf(“Enter the second number to take away from the first: “);
scanf(“%f”, &num2);
printf(“Now booleaning!n”);
answer = num1 – num2 + (rand()%10) – (rand()%10);
if (answer > 1000) answer = answer + (rand()%100) – (rand()%100);
/*answer output*/
if (answer > 0 && answer < 10000) printf("That means you have %.0f apples, i mean, uh. numbers n", answer);
if (answer 9999) printf(“The answer is: a lot, like more than four digits or somethingn”);
printf(“nnn”);
}

/*multiplication portion*/
if (sel == 3){
printf(“Enter the first number you wish to use: “);
scanf(“%f”, &num1);
printf(“that number how many times?: “);
scanf(“%f”, &num2);
printf(“Now multiplexoring!n”);
answer = (num1 + (rand()%3) – (rand()%3)) * (num2 + (rand()%3) – (rand()%3));
/*answer output*/
if (answer > 0 && answer < 10000) printf("That's like %.0f, I thinkn", answer);
if (answer 9999) printf(“The answer is: a lot, like more than four digits or somethingn”);
printf(“nnn”);
}

/*division portion*/
if (sel == 4){
printf(“Enter the first number you wish to use: “);
scanf(“%f”, &num1);
printf(“How many piles do you want to make?: “);
scanf(“%f”, &num2);
printf(“Now multiplexoring!n”);
/*make sure there is no divide by zero. because that sucks*/
if (num2 != 0){
answer = num1 / num2 + (rand()%10) – (rand()%10);
if (answer > 1000) answer = answer + (rand()%100) – (rand()%100);
/*answer output*/
if (answer > 0 && answer < 10000) printf("That's like %.0f, I thinkn", answer);
if (answer 9999) printf(“The answer is: a lot, like more than four digits or somethingn”);
}
if (num2 == 0){
printf(“ARE YOU TRYING TO KILL ME OR SOMETHING? BYE!nn”);
break; /*the program is really pissed off*/
}
printf(“nnn”);
}

/*quantum calculus*/
if (sel == 5){
printf(“nnNow cal… Uh, you know, It’s been a long time since school and all.n”);
printf(“I’m like sort of tired and, well, why don’t you just pick a simpler one.nnn”);
}

/*exit*/
if (sel == 6) loop = 1;
}
return (0);
}

However, there was one very un-obvious parameter in the set up file, which, if you got wrong, would pass completely unnoticed until some bright spark in accounts noticed that it was churning out numbers, as it should — but they were the wrong numbers! 

Ahhh… red-faced days in my career. Happy memories! (sort of!) 

However, I agree with everyone else who thinks there are some bad consequences lying in wait for the users of such a product and I hope one that subtle is not made.

So…what is the equivalent of the technology I’m using? Tin-can telephone?

Yep, that’s how I once ended up with “opera rational objectives”. ;)

Don’t people do the same with “spell check”?

Nevertheless, only one of the sample, a 12 year old boy, noticed that the calculators were deliberately programmed to give wrong answers.

My TI-86 had a minor problem where after a few months of reliable work it would get a corrupted floating point stack. So every now and then I’d get 12/3=4.00000008. 

Actually, 12/3 does equal 4.000000079771263 (±.000000000000005) at sea level. Most calculators ignore relativistic effects, but you got a real nice precision calculator.

http://video.google.com/videoplay?docid=-7064178994016272127
(Fast forward to about 4:05)