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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
847714
2Even Fibonacci Numbers
678316
3Largest Prime Factor
511983
4Largest Palindrome Product
452738
5Smallest Multiple
439221
6Sum Square Difference
444283
710 001st Prime
387216
8Largest Product in a Series
330189
9Special Pythagorean Triplet
335629
10Summation of Primes
315165
11Largest Product in a Grid
236523
12Highly Divisible Triangular Number
232870
13Large Sum
233659
14Longest Collatz Sequence
238034
15Lattice Paths
202120
16Power Digit Sum
236413
17Number Letter Counts
169699
18Maximum Path Sum I
164103
19Counting Sundays
153905
20Factorial Digit Sum
207003
21Amicable Numbers
169222
22Names Scores
155919
23Non-Abundant Sums
128791
24Lexicographic Permutations
137893
25$1000$-digit Fibonacci Number
175396
26Reciprocal Cycles
104925
27Quadratic Primes
108404
28Number Spiral Diagonals
127145
29Distinct Powers
128067
30Digit Fifth Powers
132963
31Coin Sums
104616
32Pandigital Products
89236
33Digit Cancelling Fractions
89128
34Digit Factorials
115295
35Circular Primes
103241
36Double-base Palindromes
107890
37Truncatable Primes
91209
38Pandigital Multiples
78369
39Integer Right Triangles
90170
40Champernowne's Constant
97145
41Pandigital Prime
84492
42Coded Triangle Numbers
90206
43Sub-string Divisibility
74543
44Pentagon Numbers
73055
45Triangular, Pentagonal, and Hexagonal
86586
46Goldbach's Other Conjecture
76618
47Distinct Primes Factors
72078
48Self Powers
123203
49Prime Permutations
71678
50Consecutive Prime Sum
76811