RSS FeedUse secure connection

Problems


IDDescription / TitleSolved By
1Multiples of 3 and 5
365945
2Even Fibonacci numbers
302486
3Largest prime factor
221000
4Largest palindrome product
201232
5Smallest multiple
214773
6Sum square difference
216410
710001st prime
185342
8Largest product in a series
164626
9Special Pythagorean triplet
162443
10Summation of primes
148782
11Largest product in a grid
111990
12Highly divisible triangular number
101227
13Large sum
107793
14Longest Collatz sequence
105697
15Lattice paths
87980
16Power digit sum
110525
17Number letter counts
72736
18Maximum path sum I
71309
19Counting Sundays
65782
20Factorial digit sum
100908
21Amicable numbers
70730
22Names scores
66026
23Non-abundant sums
49665
24Lexicographic permutations
57161
251000-digit Fibonacci number
77311
26Reciprocal cycles
40713
27Quadratic primes
42928
28Number spiral diagonals
57009
29Distinct powers
51456
30Digit fifth powers
54742
31Coin sums
40443
32Pandigital products
34825
33Digit canceling fractions
35957
34Digit factorials
47791
35Circular primes
43691
36Double-base palindromes
46482
37Truncatable primes
36960
38Pandigital multiples
31394
39Integer right triangles
36343
40Champernowne's constant
40720
41Pandigital prime
34046
42Coded triangle numbers
39026
43Sub-string divisibility
28922
44Pentagon numbers
27872
45Triangular, pentagonal, and hexagonal
37017
46Goldbach's other conjecture
29656
47Distinct primes factors
28501
48Self powers
61697
49Prime permutations
28203
50Consecutive prime sum
30370