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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
992306
2Even Fibonacci Numbers
791467
3Largest Prime Factor
570066
4Largest Palindrome Product
504460
5Smallest Multiple
507380
6Sum Square Difference
510677
710001st Prime
437114
8Largest Product in a Series
366598
9Special Pythagorean Triplet
371629
10Summation of Primes
340966
11Largest Product in a Grid
245187
12Highly Divisible Triangular Number
231738
13Large Sum
237038
14Longest Collatz Sequence
237432
15Lattice Paths
196249
16Power Digit Sum
239637
17Number Letter Counts
159499
18Maximum Path Sum I
152731
19Counting Sundays
141844
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
89281
27Quadratic Primes
92714
28Number Spiral Diagonals
113802
29Distinct Powers
111512
30Digit Fifth Powers
116038
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
62415
45Triangular, Pentagonal, and Hexagonal
75105
46Goldbach's Other Conjecture
65581
47Distinct Primes Factors
61796
48Self Powers
117813
49Prime Permutations
61668
50Consecutive Prime Sum
66467