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Problem Archives

The problems archives table shows problems 1 to 1006. 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
849634
2Even Fibonacci Numbers
679671
3Largest Prime Factor
512770
4Largest Palindrome Product
453395
5Smallest Multiple
439880
6Sum Square Difference
444924
710 001st Prime
387743
8Largest Product in a Series
330563
9Special Pythagorean Triplet
335997
10Summation of Primes
315469
11Largest Product in a Grid
236668
12Highly Divisible Triangular Number
232992
13Large Sum
233764
14Longest Collatz Sequence
238161
15Lattice Paths
202180
16Power Digit Sum
236489
17Number Letter Counts
169702
18Maximum Path Sum I
164108
19Counting Sundays
153886
20Factorial Digit Sum
207024
21Amicable Numbers
169206
22Names Scores
155896
23Non-Abundant Sums
128739
24Lexicographic Permutations
137836
25$1000$-digit Fibonacci Number
175369
26Reciprocal Cycles
104850
27Quadratic Primes
108348
28Number Spiral Diagonals
127074
29Distinct Powers
128011
30Digit Fifth Powers
132861
31Coin Sums
104588
32Pandigital Products
89184
33Digit Cancelling Fractions
89067
34Digit Factorials
115218
35Circular Primes
103197
36Double-base Palindromes
107805
37Truncatable Primes
91162
38Pandigital Multiples
78332
39Integer Right Triangles
90116
40Champernowne's Constant
97121
41Pandigital Prime
84454
42Coded Triangle Numbers
90138
43Sub-string Divisibility
74480
44Pentagon Numbers
73018
45Triangular, Pentagonal, and Hexagonal
86539
46Goldbach's Other Conjecture
76580
47Distinct Primes Factors
72037
48Self Powers
123162
49Prime Permutations
71631
50Consecutive Prime Sum
76767