#### Explore all Real Numbers videos

Sort by:
Filter by Topic:
Filter by Difficulty:

## Episode 1: Probability

### The Perils of Dogsitting

In this first episode we present a warm-up probability problem about dogsitting a rambunctious poodle, and review the...

## Episode 2: Probability

### Always Take the Middle Taxi

The problem of the week in this episode involves the probability of a certain arrangement of random cars at a traffic...

## Episode 3: Probability

### A Perfectly Balanced War

In this episode, we ask you to compute the probability of losing an Ace when playing a turn of the card game War, and...

## Episode 4: Probability

At the DMV, there are test takers who study, and there are those who pass. This episode’s problem investigates the re...

## Episode 5: Probability

### Grandma's Secret College Fund

A second Bayes’ Theorem problem is presented in this episode, as we sample a random bill from a piggy bank and try to...

## Episode 6: Geometry

### The Perfect Snow Cone

This episode kicks off a sequence of geometry problems, here we are figuring out the optimal dimensions of a snow con...

## Episode 7: Geometry

### Efficient Reshaping of a Snowball Into a Snow Cone

In this episode we continue with snow cone related calculations, with a bonus problem to use integration to compute t...

## Episode 8: Geometry

### Crossing the River

For your toy boat Wavey to cross the river, it must fight the current using its motor: where should you aim it?

## Episode 9: Geometry

### Crossing the River 2: Wavey's Revenge

We continue charting courses for Wavey at the riverbank, solving the previous episode’s navigation puzzle and posing ...

## Episode 10: Geometry

### The Art Thief at the Window

The problem of the week is to figure out which paintings will slide through an oddly-shaped window, the security of t...

## Episode 11: Expected Value

### The Unknown Monster

In this episode we define Expected Value and offer an introductory puzzle to the concept, along with bonus problem, a...

## Episode 12: Expected Value

### Photographing the Chaotic Marching Band

To get the perfect photo of the marching band, the rows have to be in-step, but are choosing their starting foot at r...

## Episode 13: Expected Value

### How Many Snowboards Need Sharpening?

Rachel has six snowboards, one of which gets chosen for each day. How many distinct snowboards did she expect to use?...

## Episode 14: Expected Value

### Finals Week

Jayden is preparing for finals week, and wants to know how much time can he expect between his two finals. Can you he...

## Episode 15: Expected Value

### The Half-Court Shot

We solve the problem of the expected time between Jayden’s two finals, and present the last problem of the first seas...

## Episode 16: Expected Value

### Finale

We finish off the season with a flurry of solutions to the problem of the number of half-court attempts required to m...

### Disclosures & Policies

© Copyright 2015-2021 Jane Street Group, LLC. All rights reserved. Services are provided in the U.S. by Jane Street Capital, LLC and Jane Street Execution Services, LLC, each of which is a SEC-registered broker dealer and member of FINRA (www.finra.org). Regulated activities are undertaken in Europe by Jane Street Financial Limited, an investment firm authorized and regulated by the U.K. Financial Conduct Authority, and Jane Street Netherlands B.V., an investment firm authorized and regulated by the Netherlands Authority for the Financial Markets (Autoriteit Financiële Markten), and in Hong Kong by Jane Street Hong Kong Limited, a regulated entity under the Hong Kong Securities and Futures Commission (CE No. BAL548). Each of these entities is a wholly owned subsidiary of Jane Street Group, LLC. This material is provided for informational purposes only and does not constitute an offer or solicitation for the purchase or sale of any security or other financial instrument. | Jane Street and the concentric circle mark are registered trademarks of Jane Street.