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Problem Archives

The problems archives table shows problems 1 to 1003. 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
853495
2Even Fibonacci Numbers
682517
3Largest Prime Factor
514455
4Largest Palindrome Product
454761
5Smallest Multiple
441244
6Sum Square Difference
446210
710 001st Prime
388875
8Largest Product in a Series
331251
9Special Pythagorean Triplet
336764
10Summation of Primes
316135
11Largest Product in a Grid
236918
12Highly Divisible Triangular Number
233229
13Large Sum
233986
14Longest Collatz Sequence
238370
15Lattice Paths
202261
16Power Digit Sum
236726
17Number Letter Counts
169690
18Maximum Path Sum I
164065
19Counting Sundays
153853
20Factorial Digit Sum
207009
21Amicable Numbers
169173
22Names Scores
155911
23Non-Abundant Sums
128607
24Lexicographic Permutations
137732
25$1000$-digit Fibonacci Number
175364
26Reciprocal Cycles
104729
27Quadratic Primes
108235
28Number Spiral Diagonals
126953
29Distinct Powers
127916
30Digit Fifth Powers
132705
31Coin Sums
104493
32Pandigital Products
89088
33Digit Cancelling Fractions
88942
34Digit Factorials
115086
35Circular Primes
103104
36Double-base Palindromes
107663
37Truncatable Primes
91054
38Pandigital Multiples
78248
39Integer Right Triangles
89989
40Champernowne's Constant
97018
41Pandigital Prime
84376
42Coded Triangle Numbers
90003
43Sub-string Divisibility
74375
44Pentagon Numbers
72924
45Triangular, Pentagonal, and Hexagonal
86406
46Goldbach's Other Conjecture
76487
47Distinct Primes Factors
71956
48Self Powers
123084
49Prime Permutations
71562
50Consecutive Prime Sum
76665