All problems come from https://projecteuler.net
An Euler problem a day keep his totatives away.
| Problem | Description |
|---|---|
| 01 | Find the sum of all the multiples of 3 or 5 below 1000. |
| 02 | By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms. |
| 03 | What is the largest prime factor of the number 600851475143? |
| 04 | Find the largest palindrome made from the product of two 3-digit numbers. |
| 05 | What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20? |
| 06 | Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum. |
| 07 | What is the 10 001st prime number? |
| 08 | Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product? |
| 09 | There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product abc. |
| 10 | Find the sum of all the primes below two million. |
| 11 | What is the greatest product of four adjacent numbers in the same direction (up, down, left, right, or diagonally) in the 20×20 grid? |
| 12 | 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. What is the value of the first triangle number to have over five hundred divisors? |
| 13 | Work out the first ten digits of the sum of the following one-hundred 50-digit numbers. |
| 14 | Which starting number, under one million, produces the longest chain (Collatz)? |