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Problem Archives

The problems archives table shows problems 1 to 947. If you would like to tackle the 10 most recently published problems, go to Recent problems.


ID

TitleSolved By
1Multiples of 3 or 5
1034735
2Even Fibonacci Numbers
823610
3Largest Prime Factor
593384
4Largest Palindrome Product
524122
5Smallest Multiple
526462
6Sum Square Difference
530180
710 001st Prime
453242
8Largest Product in a Series
379859
9Special Pythagorean Triplet
385066
10Summation of Primes
353821
11Largest Product in a Grid
253976
12Highly Divisible Triangular Number
240658
13Large Sum
245640
14Longest Collatz Sequence
246342
15Lattice Paths
203758
16Power Digit Sum
248439
17Number Letter Counts
165397
18Maximum Path Sum I
158365
19Counting Sundays
146999
20Factorial Digit Sum
214834
21Amicable Numbers
159666
22Names Scores
146597
23Non-Abundant Sums
114864
24Lexicographic Permutations
125595
25$1000$-digit Fibonacci Number
169323
26Reciprocal Cycles
92872
27Quadratic Primes
96350
28Number Spiral Diagonals
117710
29Distinct Powers
115683
30Digit Fifth Powers
120285
31Coin Sums
94080
32Pandigital Products
78919
33Digit Cancelling Fractions
79173
34Digit Factorials
103416
35Circular Primes
93149
36Double-base Palindromes
97269
37Truncatable Primes
81195
38Pandigital Multiples
69711
39Integer Right Triangles
80602
40Champernowne's Constant
87830
41Pandigital Prime
75367
42Coded Triangle Numbers
81609
43Sub-string Divisibility
66353
44Pentagon Numbers
65044
45Triangular, Pentagonal, and Hexagonal
77992
46Goldbach's Other Conjecture
68384
47Distinct Primes Factors
64374
48Self Powers
121852
49Prime Permutations
64189
50Consecutive Prime Sum
69277