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Problem Archives

The problems archives table shows problems 1 to 999. 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
857691
2Even Fibonacci Numbers
685519
3Largest Prime Factor
516221
4Largest Palindrome Product
456246
5Smallest Multiple
442692
6Sum Square Difference
447501
710 001st Prime
390058
8Largest Product in a Series
331991
9Special Pythagorean Triplet
337594
10Summation of Primes
316868
11Largest Product in a Grid
237170
12Highly Divisible Triangular Number
233497
13Large Sum
234213
14Longest Collatz Sequence
238620
15Lattice Paths
202366
16Power Digit Sum
236893
17Number Letter Counts
169699
18Maximum Path Sum I
164007
19Counting Sundays
153785
20Factorial Digit Sum
207019
21Amicable Numbers
169099
22Names Scores
155838
23Non-Abundant Sums
128433
24Lexicographic Permutations
137598
25$1000$-digit Fibonacci Number
175344
26Reciprocal Cycles
104576
27Quadratic Primes
108082
28Number Spiral Diagonals
126806
29Distinct Powers
127811
30Digit Fifth Powers
132568
31Coin Sums
104360
32Pandigital Products
88952
33Digit Cancelling Fractions
88783
34Digit Factorials
114942
35Circular Primes
102989
36Double-base Palindromes
107512
37Truncatable Primes
90915
38Pandigital Multiples
78135
39Integer Right Triangles
89855
40Champernowne's Constant
96925
41Pandigital Prime
84285
42Coded Triangle Numbers
89850
43Sub-string Divisibility
74261
44Pentagon Numbers
72837
45Triangular, Pentagonal, and Hexagonal
86285
46Goldbach's Other Conjecture
76386
47Distinct Primes Factors
71862
48Self Powers
123028
49Prime Permutations
71472
50Consecutive Prime Sum
76567