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Problem Archives

The problems archives table shows problems 1 to 1007. 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
848350
2Even Fibonacci Numbers
678774
3Largest Prime Factor
512233
4Largest Palindrome Product
452954
5Smallest Multiple
439447
6Sum Square Difference
444494
710 001st Prime
387399
8Largest Product in a Series
330308
9Special Pythagorean Triplet
335747
10Summation of Primes
315263
11Largest Product in a Grid
236575
12Highly Divisible Triangular Number
232911
13Large Sum
233696
14Longest Collatz Sequence
238078
15Lattice Paths
202136
16Power Digit Sum
236433
17Number Letter Counts
169688
18Maximum Path Sum I
164095
19Counting Sundays
153888
20Factorial Digit Sum
207011
21Amicable Numbers
169215
22Names Scores
155900
23Non-Abundant Sums
128768
24Lexicographic Permutations
137865
25$1000$-digit Fibonacci Number
175365
26Reciprocal Cycles
104891
27Quadratic Primes
108387
28Number Spiral Diagonals
127116
29Distinct Powers
128045
30Digit Fifth Powers
132916
31Coin Sums
104613
32Pandigital Products
89214
33Digit Cancelling Fractions
89107
34Digit Factorials
115266
35Circular Primes
103220
36Double-base Palindromes
107858
37Truncatable Primes
91191
38Pandigital Multiples
78356
39Integer Right Triangles
90148
40Champernowne's Constant
97137
41Pandigital Prime
84479
42Coded Triangle Numbers
90176
43Sub-string Divisibility
74520
44Pentagon Numbers
73045
45Triangular, Pentagonal, and Hexagonal
86572
46Goldbach's Other Conjecture
76604
47Distinct Primes Factors
72062
48Self Powers
123180
49Prime Permutations
71661
50Consecutive Prime Sum
76796