Problem 4: A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99. Find the largest palindrome made from the product of two 3-digit numbers. Firstly I decided to try and solve the problem using two 2-digit numbers so I can […]

# Tag: project-euler

Problem 3 : The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? To solve this, I needed to understand the process of prime factorisation (surprisingly, it is something which I was never taught at school/uni). What we need to do, is to […]

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, 13, 21, 34, 55, 89, … By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the […]

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 the multiples of 3 or 5 below 1000. To solve this in a brute force manner, we can count up […]