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Problems Archives

The problems archives table shows problems 1 to 745. 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.


ID

Description / TitleSolved By
1Multiples of 3 and 5
966298
2Even Fibonacci numbers
769917
3Largest prime factor
552777
4Largest palindrome product
488696
5Smallest multiple
492158
6Sum square difference
495206
710001st prime
423490
8Largest product in a series
354318
9Special Pythagorean triplet
359561
10Summation of primes
329244
11Largest product in a grid
235656
12Highly divisible triangular number
222349
13Large sum
227609
14Longest Collatz sequence
227931
15Lattice paths
187848
16Power digit sum
230256
17Number letter counts
152192
18Maximum path sum I
145620
19Counting Sundays
135289
20Factorial digit sum
199207
21Amicable numbers
146980
22Names scores
134988
23Non-abundant sums
104451
24Lexicographic permutations
115040
251000-digit Fibonacci number
156065
26Reciprocal cycles
84069
27Quadratic primes
87469
28Number spiral diagonals
108370
29Distinct powers
105694
30Digit fifth powers
110326
31Coin sums
85177
32Pandigital products
71267
33Digit cancelling fractions
71701
34Digit factorials
94391
35Circular primes
84698
36Double-base palindromes
88868
37Truncatable primes
73576
38Pandigital multiples
62943
39Integer right triangles
73135
40Champernowne's constant
80071
41Pandigital prime
68011
42Coded triangle numbers
74350
43Sub-string divisibility
59703
44Pentagon numbers
58354
45Triangular, pentagonal, and hexagonal
70921
46Goldbach's other conjecture
61486
47Distinct primes factors
57816
48Self powers
112376
49Prime permutations
57754
50Consecutive prime sum
62333