Counting
47 problems
Reachable lengths from given bars
Length of overlapping strips
Count coin combinations for an amount
List all three-digit numbers from cards
Build values from place-valued items
Count segments joining points on a loop
Count outcomes with a table
Count digits used over a range
How often a number appears in the table
Count numbers formed from digit cards
Count outcomes with the multiplication rule
Counting Measurable Lengths
Counting shortest grid paths
Sum of all numbers from digit cards
Log Cutting: Cuts, Pieces, and Time
Building fractions from number cards
Fractions meeting given conditions
Counting segments, lines, and rays
Distinct masses weighable with given weights
Trees along a road (fencepost)
Segments joining points on a circle
Counting palindromic numbers
Count digits used over a range
Count how often each digit appears
Count acute angles among intersecting lines
Numbers whose quotient equals the remainder
Count handshakes in a group
Count games in a knockout tournament
Count shortest routes on a grid
Shortest edge routes on a solid
Shortest routes through a required stop
Count segments and triangles from marked points
Count divisors with a Hasse diagram
Count primes with the sieve of Eratosthenes
Trailing zeros from pairs of 2 and 5
Who sits opposite in a circle
Count distinct arrangements up to rotation
Fair games and comparing likelihoods
Permutations versus combinations
Addition and multiplication counting rules
Best and worst case draws for a pair
People needed for three shared birthdays
Pigeonhole applied to digit-card numbers
Counting painted unit cubes
Faces, edges, vertices and Euler's formula
Count distinct stackings up to symmetry
Surface area of a complicated cube stack