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Problem Archives

The problems archives table shows problems 1 to 956. If you would like to tackle the 10 most recently published problems, go to Recent problems.


ID

TitleSolved By
1Multiples of 3 or 5
1040422
2Even Fibonacci Numbers
827915
3Largest Prime Factor
596547
4Largest Palindrome Product
526755
5Smallest Multiple
529040
6Sum Square Difference
532788
710 001st Prime
455426
8Largest Product in a Series
381654
9Special Pythagorean Triplet
386848
10Summation of Primes
355574
11Largest Product in a Grid
255131
12Highly Divisible Triangular Number
241818
13Large Sum
246728
14Longest Collatz Sequence
247526
15Lattice Paths
204737
16Power Digit Sum
249576
17Number Letter Counts
166143
18Maximum Path Sum I
159129
19Counting Sundays
147669
20Factorial Digit Sum
215771
21Amicable Numbers
160419
22Names Scores
147241
23Non-Abundant Sums
115427
24Lexicographic Permutations
126136
25$1000$-digit Fibonacci Number
170110
26Reciprocal Cycles
93310
27Quadratic Primes
96820
28Number Spiral Diagonals
118216
29Distinct Powers
116180
30Digit Fifth Powers
120793
31Coin Sums
94547
32Pandigital Products
79323
33Digit Cancelling Fractions
79552
34Digit Factorials
103903
35Circular Primes
93598
36Double-base Palindromes
97687
37Truncatable Primes
81592
38Pandigital Multiples
70049
39Integer Right Triangles
80986
40Champernowne's Constant
88205
41Pandigital Prime
75742
42Coded Triangle Numbers
81983
43Sub-string Divisibility
66680
44Pentagon Numbers
65374
45Triangular, Pentagonal, and Hexagonal
78364
46Goldbach's Other Conjecture
68757
47Distinct Primes Factors
64700
48Self Powers
122364
49Prime Permutations
64524
50Consecutive Prime Sum
69634