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Problem Archives

The problems archives table shows problems 1 to 872. If you would like to tackle the 10 most recently published problems, go to Recent problems.


ID

TitleSolved By
1Multiples of 3 or 5
992304
2Even Fibonacci Numbers
791467
3Largest Prime Factor
570066
4Largest Palindrome Product
504460
5Smallest Multiple
507380
6Sum Square Difference
510676
710001st Prime
437111
8Largest Product in a Series
366596
9Special Pythagorean Triplet
371628
10Summation of Primes
340965
11Largest Product in a Grid
245187
12Highly Divisible Triangular Number
231738
13Large Sum
237038
14Longest Collatz Sequence
237430
15Lattice Paths
196247
16Power Digit Sum
239635
17Number Letter Counts
159497
18Maximum Path Sum I
152728
19Counting Sundays
141842
20Factorial Digit Sum
207541
21Amicable Numbers
154003
22Names Scores
141604
23Non-Abundant Sums
110379
24Lexicographic Permutations
121104
25$1000$-digit Fibonacci Number
163322
26Reciprocal Cycles
89280
27Quadratic Primes
92713
28Number Spiral Diagonals
113801
29Distinct Powers
111511
30Digit Fifth Powers
116036
31Coin Sums
90400
32Pandigital Products
75806
33Digit Cancelling Fractions
76150
34Digit Factorials
99584
35Circular Primes
89690
36Double-base Palindromes
93841
37Truncatable Primes
78067
38Pandigital Multiples
67042
39Integer Right Triangles
77614
40Champernowne's Constant
84739
41Pandigital Prime
72421
42Coded Triangle Numbers
78760
43Sub-string Divisibility
63773
44Pentagon Numbers
62414
45Triangular, Pentagonal, and Hexagonal
75104
46Goldbach's Other Conjecture
65580
47Distinct Primes Factors
61796
48Self Powers
117813
49Prime Permutations
61668
50Consecutive Prime Sum
66467