WORKED EXAMPLE30,000 × 0.85⁶

depreciation.mov

how do credits work?One credit makes one video. Step 1: ...

credits.txt

def search(a, t): lo, hi = 0, len(a) - 1 while lo <= hi: mid = (lo + hi) // 2 ...

big-o.py

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sticky.note

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worked examples

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topics.md

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projectile.mov

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guides, ideas and worked examples

start-here.md

start here

How Doubtster works

Ask a question, read the answer, and turn it into a short explainer video when you want to see it worked out.

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1Askchat is free

2Readstep by step

3Watch1 credit a video

all articles

13 articles

start-here-how-doubtster-w.md

Guides5 min read

Start here: how Doubtster works

Ask a question, read the answer, and turn it into a short explainer video when you want to see it worked out.

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how-the-7-day-trial-works.md

Guides4 min read

How the 7 day trial works

The trial costs $1.99, runs for 7 days and includes 3 videos. Here is what happens on day 7, and how to cancel in time.

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credits-explained.md

Guides3 min read

Credits explained

One credit makes one video. Here is how plan credits, trial credits and top-ups behave.

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what-we-are-building-next.md

Product updates3 min read

What we are building next

An honest look at what works today and what is on the way. No dates, because we would rather ship than promise.

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why-we-build-videos-from-c.md

Behind the scenes6 min read

Why we build videos from code

Every explainer is generated from a script, so equations stay exact and the picture matches the words.

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reducing-balance-depreciat.md

Worked examplesMaths6 min read

Reducing balance depreciation, step by step

A $30,000 car loses 15% of its value each year. Work out what it is worth after six years.

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turn-a-wrong-answer-into-a.md

Study tips4 min read

Turn a wrong answer into a revision note

A mistake is the most useful thing on your page. Here is a three line way to keep it.

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how-we-think-about-accurac.md

Behind the scenes5 min read

How we think about accuracy

AI explanations can be wrong. What we do about it, and what we ask you to do.

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velocity-and-acceleration.md

Worked examplesPhysics7 min read

Velocity and acceleration, worked through

A car speeds up from rest. Find its acceleration and how far it travels, one step at a time.

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ask-a-question-that-gets-a.md

Study tips5 min read

Ask a question that gets a clearer explanation

A little context in your question makes the answer fit you much better.

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supply-and-demand-equilibr.md

Worked examplesEconomics5 min read

Supply and demand: finding equilibrium

Given demand and supply equations, find the price where the market clears.

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a-simple-weekly-revision-p.md

Study tips5 min read

A simple weekly revision plan

Short and often beats long and rare. A plan you can actually keep.

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big-o-notation-deck-of-car.md

Worked examplesCoding8 min read

Big O notation with a deck of cards

Find a card in a deck three ways and see why some methods stop working as the pile grows.

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worked-examples

worked examples

Real questions solved one step at a time, across maths, physics, economics and coding.

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