"I knew this was going to happen." — Super Computer[source]
The Super Computer is a machine that can answer any question. In order to find out what the nicest thing they can do for their mother is, Phineas and Ferb build a super computer that can answer any question it is presented with. ("Ask a Foolish Question") It does so by analyzing data from all the events in the Tri-State Area and predicting what will happen
Design and construction
The super computer is built on a metallic platform, with a large C-like metal bar with many holes for the "neck." It has two large TV's with green screens for eyes, and five computers close together with red screen for the mouth. It has many wires connecting the screens to the neck, and is plugged in an unknown location. It is shown how it was built in Buildin' a Supercomputer.
The questions are italicized and the Super Computer's answers are in bold.
(Phineas) Okay, computer, are you ready to answer any question?Yes, my data is complete, my logic infallible.
(Phineas) What's 2 + 2?4. perhaps you should just count on your fingers.
(Phineas) What's the square root of 72,361?269.
(Isabella) What are the names of the girls in my Fireside Girls troop? Gretchen, Adyson, Holly, Katie, Milly, and Ginger.
(Baljeet) On a multi-valve engine with variable timing how can I isolate an exhaust pipe leak without removing the camshaft? Coat the engine with tomato paste and the leak will reveal itself.
(Buford) Um... what size pants do I wear?Boys' husky extra-large.
(Phineas) What is the nicest thing we can do for mom today? Get a gallon of industrial marking dye and a leaf blower, tie balloons onto them, then go to the top of Danville Hill, and at 2:37 PM, release them into the wind.
(Phineas) Really?Nothing could make your mother happier today.
(Candace) What, is, that? I am a Super Computer, I can answer any question you could possibly ask.
(Candace) Did my brothers make you? Yes, yes they did.
(Candace) How many states are in the United States?50.
(Candace) What goes on top of pancakes?Butter and syrup.
(Candace) How do you pronounce the J in jalapeno? It makes the H sound.
(Candace) How many fingers are behind my back? Two.
(Candace) How can I get my mom to see what my brothers had done?Elementary, you must build a device that makes your mom see what your brothers had done.
(Candace) What kind of device?Follow my instructions to the letter and when you finish I have a 100% certain that your mom will see what your brothers had done.
(Candace) Okay, where do I start?You are going to need a toaster, a number 2 screwdriver, some electrical tape...
(Candace) There, finished, did I put it all together?You built it perfectly, Candace, your mom will definitely see what the boys had done, and you finished just in time because in two seconds your mom is going to pull up.
Doofenshmirtz's machine grabbed a key directly below the super computer, and carried it to D.E.I. There, it destroyed Doofenshmirtz's All-Purpose-Inator and the computer exploded.