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Problem Archives

The problems archives table shows problems 1 to 972. 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
1035947
2Even Fibonacci Numbers
823843
3Largest Prime Factor
593140
4Largest Palindrome Product
523651
5Smallest Multiple
525938
6Sum Square Difference
529660
710 001st Prime
452634
8Largest Product in a Series
379272
9Special Pythagorean Triplet
384417
10Summation of Primes
353316
11Largest Product in a Grid
253611
12Highly Divisible Triangular Number
240282
13Large Sum
245179
14Longest Collatz Sequence
245937
15Lattice Paths
203560
16Power Digit Sum
248061
17Number Letter Counts
165307
18Maximum Path Sum I
158375
19Counting Sundays
147004
20Factorial Digit Sum
214583
21Amicable Numbers
159668
22Names Scores
146629
23Non-Abundant Sums
115076
24Lexicographic Permutations
125756
25$1000$-digit Fibonacci Number
169334
26Reciprocal Cycles
93152
27Quadratic Primes
96640
28Number Spiral Diagonals
117933
29Distinct Powers
115855
30Digit Fifth Powers
120461
31Coin Sums
94359
32Pandigital Products
79225
33Digit Cancelling Fractions
79448
34Digit Factorials
103676
35Circular Primes
93437
36Double-base Palindromes
97502
37Truncatable Primes
81488
38Pandigital Multiples
69997
39Integer Right Triangles
80872
40Champernowne's Constant
88034
41Pandigital Prime
75646
42Coded Triangle Numbers
81874
43Sub-string Divisibility
66642
44Pentagon Numbers
65324
45Triangular, Pentagonal, and Hexagonal
78267
46Goldbach's Other Conjecture
68677
47Distinct Primes Factors
64653
48Self Powers
121953
49Prime Permutations
64470
50Consecutive Prime Sum
69552