Following are solutions to some of the problems in Project Euler

1. Multiples of 3 and 5
2. Even Fibonacci numbers
3. Largest prime factor
4. Largest palindrome product
5. Smallest multiple
6. Sum square difference
7. 10001st prime
8. Largest product in a series
9. Special Pythagorean triplet
10. Summation of primes
11. Largest product in a grid
12. Highly divisible triangular number
13. Longest Collatz sequence