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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
852032
2Even Fibonacci Numbers
681394
3Largest Prime Factor
513816
4Largest Palindrome Product
454220
5Smallest Multiple
440752
6Sum Square Difference
445748
710 001st Prime
388457
8Largest Product in a Series
331009
9Special Pythagorean Triplet
336513
10Summation of Primes
315904
11Largest Product in a Grid
236846
12Highly Divisible Triangular Number
233144
13Large Sum
233907
14Longest Collatz Sequence
238288
15Lattice Paths
202239
16Power Digit Sum
236611
17Number Letter Counts
169694
18Maximum Path Sum I
164105
19Counting Sundays
153878
20Factorial Digit Sum
207039
21Amicable Numbers
169189
22Names Scores
155864
23Non-Abundant Sums
128653
24Lexicographic Permutations
137773
25$1000$-digit Fibonacci Number
175376
26Reciprocal Cycles
104789
27Quadratic Primes
108287
28Number Spiral Diagonals
126995
29Distinct Powers
127961
30Digit Fifth Powers
132755
31Coin Sums
104534
32Pandigital Products
89130
33Digit Cancelling Fractions
88999
34Digit Factorials
115143
35Circular Primes
103143
36Double-base Palindromes
107723
37Truncatable Primes
91101
38Pandigital Multiples
78285
39Integer Right Triangles
90046
40Champernowne's Constant
97066
41Pandigital Prime
84414
42Coded Triangle Numbers
90060
43Sub-string Divisibility
74426
44Pentagon Numbers
72979
45Triangular, Pentagonal, and Hexagonal
86471
46Goldbach's Other Conjecture
76528
47Distinct Primes Factors
71990
48Self Powers
123130
49Prime Permutations
71586
50Consecutive Prime Sum
76711