RSS Feedsecure_iconYou are currently using a secure connection

Problems Archives

The problems archives table shows problems 1 to 564. If you would like to tackle the 10 most recently published problems then go to Recent problems.
Click the description/title of the problem to view details and submit your answer.


IDDescription / TitleSolved By
1Multiples of 3 and 5
606008
2Even Fibonacci numbers
492130
3Largest prime factor
354575
4Largest palindrome product
317832
5Smallest multiple
328520
6Sum square difference
330439
710001st prime
283085
8Largest product in a series
241814
9Special Pythagorean triplet
242864
10Summation of primes
223138
11Largest product in a grid
163532
12Highly divisible triangular number
151413
13Large sum
157419
14Longest Collatz sequence
156019
15Lattice paths
129494
16Power digit sum
159288
17Number letter counts
106168
18Maximum path sum I
102581
19Counting Sundays
95070
20Factorial digit sum
141345
21Amicable numbers
102242
22Names scores
94765
23Non-abundant sums
72426
24Lexicographic permutations
81213
251000-digit Fibonacci number
109787
26Reciprocal cycles
58715
27Quadratic primes
61546
28Number spiral diagonals
78332
29Distinct powers
73785
30Digit fifth powers
77505
31Coin sums
58817
32Pandigital products
49928
33Digit cancelling fractions
50808
34Digit factorials
66925
35Circular primes
60626
36Double-base palindromes
63964
37Truncatable primes
52124
38Pandigital multiples
44366
39Integer right triangles
51471
40Champernowne's constant
57042
41Pandigital prime
47994
42Coded triangle numbers
53579
43Sub-string divisibility
41603
44Pentagon numbers
40301
45Triangular, pentagonal, and hexagonal
50886
46Goldbach's other conjecture
42717
47Distinct primes factors
40537
48Self powers
82359
49Prime permutations
40472
50Consecutive prime sum
43453