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Problem Archives

The problems archives table shows problems 1 to 1006. 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
850055
2Even Fibonacci Numbers
679990
3Largest Prime Factor
512969
4Largest Palindrome Product
453570
5Smallest Multiple
440051
6Sum Square Difference
445110
710 001st Prime
387881
8Largest Product in a Series
330662
9Special Pythagorean Triplet
336102
10Summation of Primes
315557
11Largest Product in a Grid
236708
12Highly Divisible Triangular Number
233035
13Large Sum
233807
14Longest Collatz Sequence
238198
15Lattice Paths
202200
16Power Digit Sum
236544
17Number Letter Counts
169710
18Maximum Path Sum I
164120
19Counting Sundays
153895
20Factorial Digit Sum
207048
21Amicable Numbers
169206
22Names Scores
155886
23Non-Abundant Sums
128724
24Lexicographic Permutations
137828
25$1000$-digit Fibonacci Number
175384
26Reciprocal Cycles
104844
27Quadratic Primes
108338
28Number Spiral Diagonals
127067
29Distinct Powers
128001
30Digit Fifth Powers
132850
31Coin Sums
104583
32Pandigital Products
89172
33Digit Cancelling Fractions
89057
34Digit Factorials
115210
35Circular Primes
103189
36Double-base Palindromes
107791
37Truncatable Primes
91146
38Pandigital Multiples
78320
39Integer Right Triangles
90097
40Champernowne's Constant
97115
41Pandigital Prime
84444
42Coded Triangle Numbers
90120
43Sub-string Divisibility
74470
44Pentagon Numbers
73009
45Triangular, Pentagonal, and Hexagonal
86532
46Goldbach's Other Conjecture
76574
47Distinct Primes Factors
72028
48Self Powers
123166
49Prime Permutations
71619
50Consecutive Prime Sum
76757