Need Help?
Need help finding the right class? Have a question about how classes work?
Introduction to Counting & ProbabilityFundamentals of counting and probability, including casework, multiplication, permutations, combinations, Pascal's triangle, probability, combinatorial identities, and the Binomial Theorem. 
12 weeks 
12 weeks ARE YOU READY? DO YOU NEED THIS? SYLLABUS 
Schedule
Sunday
Jul 12  Oct 4 
7:30  9:00
PM ET
Jul 12  Oct 4
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
Achilleas Sinefakopoulos 
$340
$385 w/books

$340
CLOSED
With Books $385

Wednesday
Aug 12  Oct 28 
7:30  9:00
PM ET
Aug 12  Oct 28
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
Alyssa Zisk 
$340
$385 w/books

$340
ENROLL
With Books $385

Monday
Aug 24  Nov 16 
7:30  9:00
PM ET
Aug 24  Nov 16
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
sarahmarie belcastro 
$340
$385 w/books

$340
ENROLL
With Books $385

Thursday
Sep 3  Nov 19 
7:30  9:00
PM ET
Sep 3  Nov 19
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
Luis Finotti 
$340
$385 w/books

$340
ENROLL
With Books $385

Friday
Sep 4  Nov 20 
7:30  9:00
PM ET
Sep 4  Nov 20
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
Brian Edwards 
$340
$385 w/books

$340
ENROLL
With Books $385

Monday
Sep 14  Dec 7 
7:30  9:00
PM ET
Sep 14  Dec 7
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
TBA 
$340
$385 w/books

$340
ENROLL
With Books $385

Tuesday
Sep 15  Dec 8 
7:30  9:00
PM ET
Sep 15  Dec 8
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
Jerry Leung 
$340
$385 w/books

$340
ENROLL
With Books $385

Monday
Oct 19  Jan 25 
7:30  9:00
PM ET
Oct 19  Jan 25
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
James Sheldon 
$340
$385 w/books

$340
ENROLL
With Books $385

Wednesday
Nov 11  Feb 17 
7:30  9:00
PM ET
Nov 11  Feb 17
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
James Sheldon 
$340
$385 w/books

$340
ENROLL
With Books $385

Thursday
Dec 10  Mar 11 
7:30  9:00
PM ET
Dec 10  Mar 11
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
Carl Yerger 
$340
$385 w/books

$340
ENROLL
With Books $385

Sunday
Dec 13  Mar 14 
7:30  9:00
PM ET
Dec 13  Mar 14
7:30  9:00 PM Eastern 6:30  8:00 PM Central 5:30  7:00 PM Mountain 4:30  6:00 PM Pacific Click here to see more time zones 
sarahmarie belcastro 
$340
$385 w/books

$340
ENROLL
With Books $385

Spring 2021  This course will be offered in Spring 2021. Click here to join our mailing list to be notified when the course schedule is available. 
AoPS Holidays
There are no classes September 5–7, November 23–29, and December 21–January 3.
Who Should Take?
This course is appropriate for students in grades 69 who have mastered basic algebra up through solving linear equations and manipulating multivariable expressions. Students who have completed our Introduction to Algebra A course should have sufficient background. This course is roughly the same difficulty as our Introduction to Number Theory class. For those preparing for contests, this course should help with MATHCOUNTS and the AMC 8/10/12 tests.Lessons
Lesson 1  Lists, Venn Diagrams, Addition, Multiplication 
Lesson 2  Casework, Constructions, and Restriction 
Lesson 3  Overcounting and Combinations 
Lesson 4  Combinations and Distinguishability 
Lesson 5  Challenging Problems Day 
Lesson 6  Introduction to Probability 
Lesson 7  Probability and Arithmetic 
Lesson 8  Geometric Probability, Think About It!, and Expected Value 
Lesson 9  Pascal's Triangle and Identities 
Lesson 10  The Hockey Stick Identity 
Lesson 11  The Binomial Theorem 
Lesson 12  Challenging Problems Day 2 
Required Textbook
Introduction to Counting & Probability
A thorough introduction for students in grades 710 to counting and probability topics such as permutations, combinations, Pascal's triangle, geometric probability, basic combinatorial identities, the Binomial Theorem, and more.
