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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
848749
2Even Fibonacci Numbers
679067
3Largest Prime Factor
512417
4Largest Palindrome Product
453120
5Smallest Multiple
439599
6Sum Square Difference
444645
710 001st Prime
387507
8Largest Product in a Series
330387
9Special Pythagorean Triplet
335825
10Summation of Primes
315334
11Largest Product in a Grid
236612
12Highly Divisible Triangular Number
232938
13Large Sum
233724
14Longest Collatz Sequence
238111
15Lattice Paths
202161
16Power Digit Sum
236452
17Number Letter Counts
169697
18Maximum Path Sum I
164101
19Counting Sundays
153895
20Factorial Digit Sum
207016
21Amicable Numbers
169219
22Names Scores
155899
23Non-Abundant Sums
128761
24Lexicographic Permutations
137855
25$1000$-digit Fibonacci Number
175365
26Reciprocal Cycles
104878
27Quadratic Primes
108375
28Number Spiral Diagonals
127104
29Distinct Powers
128042
30Digit Fifth Powers
132907
31Coin Sums
104609
32Pandigital Products
89207
33Digit Cancelling Fractions
89099
34Digit Factorials
115258
35Circular Primes
103216
36Double-base Palindromes
107842
37Truncatable Primes
91187
38Pandigital Multiples
78349
39Integer Right Triangles
90140
40Champernowne's Constant
97137
41Pandigital Prime
84474
42Coded Triangle Numbers
90166
43Sub-string Divisibility
74506
44Pentagon Numbers
73033
45Triangular, Pentagonal, and Hexagonal
86555
46Goldbach's Other Conjecture
76596
47Distinct Primes Factors
72057
48Self Powers
123177
49Prime Permutations
71651
50Consecutive Prime Sum
76790