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Problem Archives

The problems archives table shows problems 1 to 1005. 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
850432
2Even Fibonacci Numbers
680268
3Largest Prime Factor
513128
4Largest Palindrome Product
453707
5Smallest Multiple
440174
6Sum Square Difference
445245
710 001st Prime
387991
8Largest Product in a Series
330742
9Special Pythagorean Triplet
336173
10Summation of Primes
315619
11Largest Product in a Grid
236744
12Highly Divisible Triangular Number
233061
13Large Sum
233848
14Longest Collatz Sequence
238238
15Lattice Paths
202226
16Power Digit Sum
236559
17Number Letter Counts
169710
18Maximum Path Sum I
164118
19Counting Sundays
153885
20Factorial Digit Sum
207047
21Amicable Numbers
169200
22Names Scores
155885
23Non-Abundant Sums
128713
24Lexicographic Permutations
137822
25$1000$-digit Fibonacci Number
175394
26Reciprocal Cycles
104838
27Quadratic Primes
108328
28Number Spiral Diagonals
127054
29Distinct Powers
127994
30Digit Fifth Powers
132831
31Coin Sums
104576
32Pandigital Products
89164
33Digit Cancelling Fractions
89046
34Digit Factorials
115197
35Circular Primes
103185
36Double-base Palindromes
107774
37Truncatable Primes
91142
38Pandigital Multiples
78322
39Integer Right Triangles
90092
40Champernowne's Constant
97110
41Pandigital Prime
84441
42Coded Triangle Numbers
90112
43Sub-string Divisibility
74466
44Pentagon Numbers
73011
45Triangular, Pentagonal, and Hexagonal
86524
46Goldbach's Other Conjecture
76571
47Distinct Primes Factors
72025
48Self Powers
123167
49Prime Permutations
71619
50Consecutive Prime Sum
76751