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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
849455
2Even Fibonacci Numbers
679550
3Largest Prime Factor
512716
4Largest Palindrome Product
453368
5Smallest Multiple
439857
6Sum Square Difference
444897
710 001st Prime
387709
8Largest Product in a Series
330544
9Special Pythagorean Triplet
335977
10Summation of Primes
315450
11Largest Product in a Grid
236671
12Highly Divisible Triangular Number
232989
13Large Sum
233757
14Longest Collatz Sequence
238146
15Lattice Paths
202180
16Power Digit Sum
236490
17Number Letter Counts
169707
18Maximum Path Sum I
164114
19Counting Sundays
153895
20Factorial Digit Sum
207038
21Amicable Numbers
169211
22Names Scores
155905
23Non-Abundant Sums
128751
24Lexicographic Permutations
137844
25$1000$-digit Fibonacci Number
175372
26Reciprocal Cycles
104862
27Quadratic Primes
108360
28Number Spiral Diagonals
127079
29Distinct Powers
128019
30Digit Fifth Powers
132878
31Coin Sums
104594
32Pandigital Products
89189
33Digit Cancelling Fractions
89077
34Digit Factorials
115231
35Circular Primes
103206
36Double-base Palindromes
107812
37Truncatable Primes
91169
38Pandigital Multiples
78342
39Integer Right Triangles
90126
40Champernowne's Constant
97130
41Pandigital Prime
84459
42Coded Triangle Numbers
90152
43Sub-string Divisibility
74492
44Pentagon Numbers
73025
45Triangular, Pentagonal, and Hexagonal
86547
46Goldbach's Other Conjecture
76586
47Distinct Primes Factors
72043
48Self Powers
123169
49Prime Permutations
71636
50Consecutive Prime Sum
76778