For engineering and physics majors Don't retake Calc II. The Engineering Stack is nine apps built for the weeder sequence: solve algebra by hand, compute anything a TI-89 can't, and keep every equation you're expected to just know. Built by an engineering student who needed them.
Grade guarantee: use it through the term and your grade doesn't go up, we refund it.
$1,500 What one retake of Calc II costs in tuition at an average public university.
A semester What a retake costs in time. Every course behind it slides a term.
$39 What the stack costs for that same term. Refunded if your grade doesn't move.
Three tools that don't exist anywhere else These are the reason to buy. Nothing free replaces them, so there's nothing to price-shop against.
Only here Equose An interactive board that makes solving equations fun.
Click terms to move them legally across the equals sign Drag to reorder, split into branches, and explore every path Never solves for you; every move is yours, tracked as a solution tree Only here Equose Calculator A scientific calculator that goes far past the TI-84.
Integrals, derivatives, equation solving, product log, complex numbers, matrices, units, statistics Live MathJax typesetting and one-line custom function definitions Physics and Chemistry modes with built-in constants and molar masses Only here Lubben Notemaster Terms and equations, beautifully kept.
Every equation links to its terms, and every term to its equations SI-unit color coding keeps quantities unambiguous at a glance Live MathJax rendering with workspaces to organize by course Five more apps, included Every one of these is sold on its own for $4 a month. In the stack they cost nothing extra.
Memory Flashcards with spaced repetition that sticks. Normally $4/mo Meridian Know your GPA before the semester does. Normally $4/mo Course Mapper Map your entire degree as a prerequisite graph. Normally $4/mo Lightbulb Notemaster Terms that light up the terms they build on. Normally $4/mo Syllable Every course, its week, its work, and its links in one place. Normally $4/mo $240 a year of tools included with every stack, at no extra charge.
Two guarantees. Both real. You should not be the one taking the risk on whether this works.
The grade guarantee Use the stack three sessions a week through the term. If your grade in the course doesn't go up, we refund the whole term.
No transcript, no screenshots, nothing to prove. We check the usage on our side, because we already log it. One email is the whole process. Email support@celedus.app and that's the whole process.
First term only, one per person.
14 days, no questions Changed your mind for any reason inside two weeks? Email us and we refund it. No form, no reason needed, no conditions at all.
This one is separate from the grade guarantee and stacks on top of it. Same address: support@celedus.app .
Pick your term A term is four months of access. Renews automatically, cancel any time, and what you already paid for keeps running.
Engineering StackMost pick this $59 $39/term
Student price with .edu
One term of access. Renews every 4 months, cancel whenever.
Equose, Equose Calculator, and Lubben Notemaster Five more apps included, worth $240 a year Everything we launch next, at no extra cost Covered by the grade guarantee Engineering Stack, year $135 $90/year
Student price with .edu
Three terms for the price of a bit over two. Summer included.
Everything in the term plan Save $27 against paying by term Keeps running through summer classes Just one app $6 $4/month
Student price with .edu
Only came for Equose? Pick any single app.
Any one app, your choice Upgrade to the stack anytime Before you ask My semester isn't exactly four months. A term is four months of access, not a lookup of your school's calendar. If yours runs longer, the next renewal picks it up before you notice.
What happens when the term ends? It renews for another four months unless you cancel. Cancel and your access runs to the end of what you already paid for.
I'm in high school, not college. Same apps, and a lot of students use them to get ahead in math early. Parents usually want the yearly plan instead.
Why is it cheaper with a .edu email? Student pricing. List is $59 a term; a verified .edu account pays $39. That's the only difference.
One term. One guarantee. No retake. Try Equose in the browser first. It takes about two minutes and nothing saves until you sign up.