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Problem Archives

The problems archives table shows problems 1 to 972. 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
1035947
2Even Fibonacci Numbers
823843
3Largest Prime Factor
593140
4Largest Palindrome Product
523651
5Smallest Multiple
525938
6Sum Square Difference
529660
710 001st Prime
452634
8Largest Product in a Series
379272
9Special Pythagorean Triplet
384419
10Summation of Primes
353316
11Largest Product in a Grid
253612
12Highly Divisible Triangular Number
240283
13Large Sum
245179
14Longest Collatz Sequence
245938
15Lattice Paths
203560
16Power Digit Sum
248062
17Number Letter Counts
165307
18Maximum Path Sum I
158375
19Counting Sundays
147005
20Factorial Digit Sum
214583
21Amicable Numbers
159668
22Names Scores
146629
23Non-Abundant Sums
115074
24Lexicographic Permutations
125754
25$1000$-digit Fibonacci Number
169334
26Reciprocal Cycles
93151
27Quadratic Primes
96639
28Number Spiral Diagonals
117932
29Distinct Powers
115855
30Digit Fifth Powers
120460
31Coin Sums
94359
32Pandigital Products
79225
33Digit Cancelling Fractions
79447
34Digit Factorials
103673
35Circular Primes
93437
36Double-base Palindromes
97498
37Truncatable Primes
81488
38Pandigital Multiples
69995
39Integer Right Triangles
80869
40Champernowne's Constant
88031
41Pandigital Prime
75643
42Coded Triangle Numbers
81870
43Sub-string Divisibility
66640
44Pentagon Numbers
65322
45Triangular, Pentagonal, and Hexagonal
78264
46Goldbach's Other Conjecture
68675
47Distinct Primes Factors
64652
48Self Powers
121949
49Prime Permutations
64467
50Consecutive Prime Sum
69550