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Problem Archives

The problems archives table shows problems 1 to 1004. 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
852684
2Even Fibonacci Numbers
681891
3Largest Prime Factor
514096
4Largest Palindrome Product
454458
5Smallest Multiple
440958
6Sum Square Difference
445963
710 001st Prime
388634
8Largest Product in a Series
331112
9Special Pythagorean Triplet
336616
10Summation of Primes
315999
11Largest Product in a Grid
236874
12Highly Divisible Triangular Number
233180
13Large Sum
233960
14Longest Collatz Sequence
238327
15Lattice Paths
202259
16Power Digit Sum
236682
17Number Letter Counts
169692
18Maximum Path Sum I
164087
19Counting Sundays
153871
20Factorial Digit Sum
207040
21Amicable Numbers
169190
22Names Scores
155893
23Non-Abundant Sums
128635
24Lexicographic Permutations
137764
25$1000$-digit Fibonacci Number
175379
26Reciprocal Cycles
104765
27Quadratic Primes
108270
28Number Spiral Diagonals
126984
29Distinct Powers
127953
30Digit Fifth Powers
132738
31Coin Sums
104523
32Pandigital Products
89117
33Digit Cancelling Fractions
88979
34Digit Factorials
115124
35Circular Primes
103128
36Double-base Palindromes
107698
37Truncatable Primes
91085
38Pandigital Multiples
78276
39Integer Right Triangles
90033
40Champernowne's Constant
97048
41Pandigital Prime
84407
42Coded Triangle Numbers
90043
43Sub-string Divisibility
74412
44Pentagon Numbers
72966
45Triangular, Pentagonal, and Hexagonal
86446
46Goldbach's Other Conjecture
76515
47Distinct Primes Factors
71983
48Self Powers
123119
49Prime Permutations
71580
50Consecutive Prime Sum
76694