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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
851785
2Even Fibonacci Numbers
681220
3Largest Prime Factor
513691
4Largest Palindrome Product
454111
5Smallest Multiple
440629
6Sum Square Difference
445652
710 001st Prime
388371
8Largest Product in a Series
330950
9Special Pythagorean Triplet
336457
10Summation of Primes
315858
11Largest Product in a Grid
236831
12Highly Divisible Triangular Number
233141
13Large Sum
233905
14Longest Collatz Sequence
238294
15Lattice Paths
202247
16Power Digit Sum
236620
17Number Letter Counts
169704
18Maximum Path Sum I
164122
19Counting Sundays
153885
20Factorial Digit Sum
207053
21Amicable Numbers
169196
22Names Scores
155868
23Non-Abundant Sums
128674
24Lexicographic Permutations
137792
25$1000$-digit Fibonacci Number
175384
26Reciprocal Cycles
104802
27Quadratic Primes
108294
28Number Spiral Diagonals
127003
29Distinct Powers
127966
30Digit Fifth Powers
132773
31Coin Sums
104542
32Pandigital Products
89142
33Digit Cancelling Fractions
89009
34Digit Factorials
115157
35Circular Primes
103159
36Double-base Palindromes
107739
37Truncatable Primes
91111
38Pandigital Multiples
78294
39Integer Right Triangles
90051
40Champernowne's Constant
97072
41Pandigital Prime
84425
42Coded Triangle Numbers
90069
43Sub-string Divisibility
74437
44Pentagon Numbers
72989
45Triangular, Pentagonal, and Hexagonal
86485
46Goldbach's Other Conjecture
76545
47Distinct Primes Factors
72009
48Self Powers
123141
49Prime Permutations
71594
50Consecutive Prime Sum
76725