Problem 2: Even Fibonacci Numbers (5ms)

Link: http://projecteuler.net/problem=2
Problem 4: Largest Palindrome product (776ms)

Link: http://projecteuler.net/problem=4
Problem 6: Sum square difference (4ms)

Link: http://projecteuler.net/problem=6
Problem 7 : 10001st prime (18ms)

Link: http://projecteuler.net/problem=7
Problem 8: Largest product in a Series (9ms)

Link: http://projecteuler.net/problem=8
Problem 9: Special Pythagorean Triplet (82ms)

Link: http://projecteuler.net/problem=9

Explanation: As a+b+c=1000 and c>b>a, (a+b)>=500 which means a<500 and
b<500.
Problem 10: Summation of primes (40ms)

Link: http://projecteuler.net/problem=10
Problem 12: Highly divisible triangular no. (5s)

Link: http://projecteuler.net/problem=12
Problem 13: Large sum (5ms)

Link: http://projecteuler.net/problem=13
Problem 14: Longest Collatz Sequence (26s)

Link: http://projecteuler.net/problem=14