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Problem Archives

The problems archives table shows problems 1 to 1004. 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
851813
2Even Fibonacci Numbers
681240
3Largest Prime Factor
513711
4Largest Palindrome Product
454124
5Smallest Multiple
440641
6Sum Square Difference
445666
710 001st Prime
388387
8Largest Product in a Series
330965
9Special Pythagorean Triplet
336468
10Summation of Primes
315872
11Largest Product in a Grid
236838
12Highly Divisible Triangular Number
233148
13Large Sum
233913
14Longest Collatz Sequence
238299
15Lattice Paths
202251
16Power Digit Sum
236623
17Number Letter Counts
169706
18Maximum Path Sum I
164124
19Counting Sundays
153889
20Factorial Digit Sum
207056
21Amicable Numbers
169201
22Names Scores
155873
23Non-Abundant Sums
128677
24Lexicographic Permutations
137797
25$1000$-digit Fibonacci Number
175389
26Reciprocal Cycles
104806
27Quadratic Primes
108294
28Number Spiral Diagonals
127007
29Distinct Powers
127966
30Digit Fifth Powers
132776
31Coin Sums
104542
32Pandigital Products
89142
33Digit Cancelling Fractions
89009
34Digit Factorials
115161
35Circular Primes
103161
36Double-base Palindromes
107742
37Truncatable Primes
91115
38Pandigital Multiples
78297
39Integer Right Triangles
90053
40Champernowne's Constant
97080
41Pandigital Prime
84426
42Coded Triangle Numbers
90070
43Sub-string Divisibility
74439
44Pentagon Numbers
72991
45Triangular, Pentagonal, and Hexagonal
86488
46Goldbach's Other Conjecture
76546
47Distinct Primes Factors
72010
48Self Powers
123145
49Prime Permutations
71595
50Consecutive Prime Sum
76727