Project Euler
Project Euler is a site full of mathematical challenges that more often than not utilize programming to solve the problem.
2020
- #176 - Right-angled triangles that share a cathetus
- #138 - Special isosceles triangles
- #187 - Semiprimes
- #173 - Using up to one million tiles how many different 'hollow' square laminae can be formed?
2019
- #162 - Hexadecimal numbers
- #110 - Diophantine reciprocals II
- #108 - Diophantine reciprocals I
- #87 - Prime power triples
- #70 - Totient permutation
- #68 - Magic 5-gon ring
- #233 - Lattice points on a circle
- #191 - Prize Strings
- #193 - Squarefree Numbers
- #139 - Pythagorean tiles
- #140 - Modified Fibonacci golden nuggets
- #137 - Fibonacci golden nuggets
- #126 - Cuboid layers
- #124 - Ordered radicals
- #86 - Cuboid route
- #74 - Digit factorial chains
- #61 - Cyclical figurate numbers
- #206 - Concealed Square
- #113 - Non-bouncy numbers
- #112 - Bouncy numbers
- #83 - Path sum: four ways
2018
- #77 - Prime summations
- #75 - Singular integer right triangles
- #125 - Palindromic sums
- #66 - Diophantine equation
- #62 - Cubic permutations
- #82 - Path sum: three ways
- 104 - Pandigital Fibonacci ends
2017
- #205 - Dice Game
- #99 - Largest exponential
- #97 - Large non-Mersenne prime
- #100 - Arranged probability
- #144 - Investigating multiple reflections of a laser beam
- #63 - Powerful digit counts
- #225 - Tribonacci non-divisors
- #73 - Counting fractions in a range
- #72 - Counting fractions
- #158 - Exploring strings for which only one character comes lexicographically after its neighbour to the left
- #151 - Paper sheets of standard sizes: an expected-value problem
- #117 - Red, green and blue tiles
- #116 - Red, green or blue tiles
- #115 - Counting block combinations II
- #114 - Counting block combinations I
- #102 - Triangle containment
- #123 - Prime square remainders
- #121 - Disc game prize fund
- #78 - Coin partitions
- #94 - Almost equilateral triangles
- #101 - Optimum polynomial
- #85 - Counting rectangles
- #84 - Monopoly odds
- #81 - Path sum: two ways
- #76 - Counting summations
- #80 - Square root digital
- #69 - Totient maximum
- #71 - Ordered fractions
- #67 - Maximum path sum II
- #59 - XOR decryption
- #58 - Spiral primes
- #57 - Square root convergents
- #56 - Powerful digit sum
- #55 - Lychrel numbers
- #52 - Permuted multiples
- #89 - Roman numerals
- #79 - Passcode derivation
- #65 - Convergents of $e$
- #64 - Odd period square roots
- #54 - Poker hands
- #92 - Square digit chains
- #50 - Consecutive prime sum
- #107 - Minimal network
- #49 - Prime permutations
- #48 - Self-powers
- #47 - Distinct prime factors
- #46 - Goldbach's other conjecture
2016
- #53 - Combinatoric selections
- #45 - Triangular, pentagonal, and hexagonal
- #44 - Pentagonal numbers
- #43 - Sub-string divisibility
- #42 - Coded triangle numbers
- #40 - Champernowne's constant
- #41 - Pandigital prime
- #39 - Integer right triangles
- #38 - Pandigital multiples
- #37 - Truncatable primes
- #36 - Double-base palindromes
- #35 - Circular primes
- #34 - Digit factorials
- #33 - Digit cancelling fractions
- #32 - Pandigital products
- #31 - Coin sums
- #30 - Digit fifth powers
- #29 - Distinct powers
- #28 - Number spiral diagonals
- #27 - Quadratic primes
- #26 - Reciprocal cycles
- #25 - 1000-digit Fibonacci number
- #24 - Lexicographic permutations
2015
- #23 - Non-abundant sums
- #22 - Names scores
- #21 - Amicable numbers
- #20 - Factorial digit sum
- #19 - Counting Sundays
- #18 - Maximum path sum I
- #17 - Number letter counts
- #16 - Power digit sum
- #15 - Lattice paths
- #14 - Longest Collatz sequence
- #13 - Large sum
- #12 - Highly divisible triangular number
- #11 - Largest product in a grid
- #10 - Summation of primes
- #9 - Special Pythagorean triplet
- #8 - Largest product in a series
- #7 - 10001st prime
- #6 - Sum square difference
- #5 - Smallest multiple
- #4 - Largest palindrome product
- #3 - Largest prime factor
- #2 - Even Fibonaci numbers
- #1 - Multiples of 3 and 5
