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Problem Archives

The problems archives table shows problems 1 to 977. If you would like to tackle the 10 most recently published problems, go to Recent problems.



ID

 Title
Solved By
1Multiples of 3 or 5
1035887
2Even Fibonacci Numbers
823780
3Largest Prime Factor
593096
4Largest Palindrome Product
523589
5Smallest Multiple
525865
6Sum Square Difference
529603
710 001st Prime
452606
8Largest Product in a Series
379251
9Special Pythagorean Triplet
384395
10Summation of Primes
353285
11Largest Product in a Grid
253605
12Highly Divisible Triangular Number
240269
13Large Sum
245165
14Longest Collatz Sequence
245921
15Lattice Paths
203551
16Power Digit Sum
248051
17Number Letter Counts
165317
18Maximum Path Sum I
158389
19Counting Sundays
147020
20Factorial Digit Sum
214580
21Amicable Numbers
159681
22Names Scores
146645
23Non-Abundant Sums
115099
24Lexicographic Permutations
125779
25$1000$-digit Fibonacci Number
169335
26Reciprocal Cycles
93199
27Quadratic Primes
96688
28Number Spiral Diagonals
117975
29Distinct Powers
115896
30Digit Fifth Powers
120507
31Coin Sums
94409
32Pandigital Products
79279
33Digit Cancelling Fractions
79518
34Digit Factorials
103727
35Circular Primes
93485
36Double-base Palindromes
97565
37Truncatable Primes
81543
38Pandigital Multiples
70056
39Integer Right Triangles
80932
40Champernowne's Constant
88090
41Pandigital Prime
75704
42Coded Triangle Numbers
81942
43Sub-string Divisibility
66702
44Pentagon Numbers
65387
45Triangular, Pentagonal, and Hexagonal
78327
46Goldbach's Other Conjecture
68744
47Distinct Primes Factors
64721
48Self Powers
122005
49Prime Permutations
64543
50Consecutive Prime Sum
69613