"Mathmagic" is the first segment of the thirtieth episode of Star vs. the Forces of Evil. It premiered on February 13, 2017 alongside "The Bounce Lounge", and is the first segment of the seventeenth episode in the second season.
When Star refuses to solve a problem in math class, she learns that avoiding her least favorite subject may have cosmic repercussions.
Miss Skullnick is teaching math and everyone, minus Marco, is incredibly bored by her lethargic way of teaching. Janna turns to Star and asks her "Why did the chicken cross the road?" followed by "To get to the other side." Star begins laughing out loud and Skullnick angrily asks her to come up to the board and solve for C. Star nonchalantly goes up and draws a kitty cat face. Infuriated, Skullnick asks her to come up and solve the problem for real. Star goes up, but instead asks Marco for help. As she decides to give up, there is a mysterious quake and Star finds herself back at her desk. However, Janna is wearing a different hat and when she asks the chicken question again, she gives a different answer. Star is confused, but once again gets Skullnick's attention. As Star gets asked to come up to the board, she is once again confused as she believes she has already done this. Again there is a quake and Star is back in her seat and Janna asks the same question, but gives a different answer. Skullnick asks Star to come up and solve for C, but once again time resets. This goes on for several more loops until Star eventually decides to go see Father Time.
Star goes to see Father Time to tell him about the time loop, but he is uninterested and leaves her behind. She is eventually confronted by Omnitraxus Prime, a member of the Magic High Commission and the ruler of space time (as opposed to time time which is what Father Time rules). According to Omnitraxus, time loops are his specialty and he explains to Star that when someone is stuck in a time loop, it means that they are stuck on a problem. After Star mentions her issue, he tells her to "do the math", but Star refuses as she is no good at math. Annoyed, Omnitraxus takes Star into a crystal cavern and reveals that there are infinite different versions of her that have all solved the problem and because she refuses, time and space is breaking apart. Unless she solves it, she will doom herself and the space time continuum.
Star finds herself back in the classroom, this time with everyone as cockroaches, and she opts to go and solve the problem on her own. As she makes her way up, reality begins to alter severely as she and the rest of the class begin to morph into different forms and reality begins to break away. Star goes up to the board and proceeds to do the math problem. While she struggles she comes out with "C=7". Everything returns to normal as she excitedly congratulates herself, but Skullnick tells her that the answer is wrong. Nevertheless, she tried and that is all that matters. Star sits down to relax as Marco tells her that it is okay and that math is hard to which she tells him "You have no idea". Skullnick then tells Marco it is his turn to answer.
- Eden Sher as Star Butterfly
- Adam McArthur as Marco Diaz
- Dee Dee Rescher as Miss Skullnick
- Jim Gaffigan as Father Time
- Carl Weathers as Omnitraxus Prime
- Abby Elliott as Janna Ordonia
- In one of the iterations of Star's time loop, Tom and Boo Fly make a cameo appearance.
- In another iteration, Miss Skullnick appears in her human form.
- In one of the iterations of the time loop, Janna says "to get to the other side" in Spanish.
- In another iteration, she says "to get to the other side" backwards.
- Among the alternate Stars seen include:
- Party Star (whose wand resembles the wand seen in the unaired pilot episode).
- Baby Star (from "Freeze Day")
- Elder Star (from "Freeze Day")
- Punk Star (from "Mr. Candle Cares")
- Warrior Star (from "School Spirit")
- Toddler Star (from "School Spirit")
- Cat Star
- Hairy Star (resembling Kelly)
- Bearded Star
- Bear suit Star
- Boy Star
- Fairy Star
- Mewberty Star (from "Mewberty")
- Link from The Legend of Zelda Star
- Royal Star (first seen in "Mewnipendance Day")
- One of the alternate Marcos seen has him with multiple heads. The Naysaya from the episode of the same name can be seen among them.
- March 8, 2017 (Israel)
- April 13, 2017 (United Kingdom and Ireland)
- May 16, 2017 (Poland)
- June 8, 2017 (Spain)
- June 28, 2017 (Latin America)
- August 4, 2017 (Southeast Asia)
- August 27, 2017 (Japan)
- October 18, 2017 (Portugal)