The problem: ———- 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 would be: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, … Let […]
You can see the original problem here: ———– In the 2020 grid below, four numbers along a diagonal line have been marked in red. 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 49 49 99 40 17 81 18 57 60 87 17 […]
Not the most challenging one, but still: The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. My Solution #include <stdio.h> #include <math.h> int isPrime(num){ int i; if (num==2) return 1; for (i=2;i<sqrt(num)+1;i++){ if (num%i==0) return 0; } […]
The problem: A Pythagorean triplet is a set of three natural numbers, a b c, for which, a2 + b2 = c2 For example, 32 + 42 = 9 + 16 = 25 = 52. There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product abc. My […]
In Problem 8 you need to find the greatest product of five consecutive digits of a 1000-digit number that is given. To find the solution I simply read the number into an array and then traversed it comparing the product of five digits at a time. #include <stdio.h> int main(){ int vet[1000]; int z,max,c,j,i=0; while(i<1000){ […]
Here’s the description of the Problem 7: By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the 10 001st prime number? In order to find the solution I wrote a simple function to test whether a number n is […]
Problem 6 has the following description: The sum of the squares of the first ten natural numbers is, 12 + 22 + … + 102 = 385 The square of the sum of the first ten natural numbers is, (1 + 2 + … + 10)2 = 552 = 3025 Hence the difference between the […]
Problem 5 was relatively easier than the ones we saw so far. Here’s the description: 2520 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 divisible by all of the numbers from 1 to 20? […]
Here’s the description for Problem 4 on Project Euler: 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. As usual the brute force approach was my first guess, […]
Problem 3 on Project Euler is another easy one. Here’s the description: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? A simple brute force approach, testing all factors of the number to see if they are prime and storing the largest […]