Project Euler

Answering all of Project Euler
… eventually.

Here you’ll find me working through answering the Project Euler problems using both R & Python (& Math of course)!

I’m treating R as a first class citizen, a feat that I think is a bit novel as the majority of members have answered using Python, C/C++, Java, & C#.

You can checkout stats on the Code Languages used by Project Euler members. Each problem showcases my original travel photography. Enjoy :)

Problem 1 - Multiples of 3 or 5
If we list all the natural numbers below \(10\) that are multiples of \(3\) or \(5\), we get \(3, 5, 6\) and \(9\). The sum of these multiples is \(23\). Find the sum of all…
January 15, 2026

February 2, 2026

Problem 2 - Even Fibonacci Numbers
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with \(1\) and \(2\), the first \(10\) terms will be: \[1, 2, 3, 5, 8…
January 15, 2026

February 2, 2026

Problem 3 - Largest Prime Factor
The prime factors of \(13195\) are \(5, 7, 13\) and \(29\).
What is the largest prime factor of the number \(600851475143\)?
January 15, 2026

February 2, 2026

Problem 4 - Largest Palindrome Product
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is \(9009 = 91 \times 99\).
Find the largest palindrome…
January 17, 2026

February 2, 2026

Problem 5 - Smallest Multiple
\(2,520\) is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
What is the smallest positive number that is evenly…
January 17, 2026

February 2, 2026

Problem 6 - Sum Square Difference
The sum of the squares of the first ten natural numbers is, \[1^2 + 2^2 + ... + 10^2 = 385.\] The square of the sum of the first ten natural numbers is, \[(1 + 2 + ... +…
January 17, 2026

February 2, 2026

Problem 7 - 10,001st Prime
By listing the first six prime numbers: \(2, 3, 5, 7, 11, 13\), we can see that the 6th prime is \(13\).
What is the \(10,001\)st prime number?
January 19, 2026

February 2, 2026

Problem 8 - Largest Product in a Series
The four adjacent digits in the \(1000\)-digit number that have the greatest product are \(9 \times 9 \times 8 \times 9 = 5832\).
January 19, 2026

February 2, 2026

Problem 9 - Special Pythagorean Triplet
A Pythagorean triplet is a set of three natural numbers, \(a \lt b \lt c\), for which, \[a^2 + b^2 = c^2.\] For example, \(3^2 + 4^2 = 9 + 16 = 25 = 5^2\).
There exists…
`January 21, 2026`{=html}
February 2, 2026

Problem 10 - Summation of Primes
The sum of the primes below \(10\) is \(2 + 3 + 5 + 7 = 17\).
Find the sum of all the primes below two million.
January 28, 2026

February 2, 2026

Problem 11 - Largest Product in a Grid
In the \(20 \times 20\) grid below, four numbers along a diagonal line have been marked in red.
February 1, 2026

February 2, 2026

Problem 12 - Highly Divisible Triangular Number
The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be \(1 + 2 + 3 + 4 + 5 + 6 + 7 = 28\). The first ten terms…
February 2, 2026

February 2, 2026
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