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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
992316
2Even Fibonacci Numbers
791475
3Largest Prime Factor
570072
4Largest Palindrome Product
504464
5Smallest Multiple
507384
6Sum Square Difference
510679
710001st Prime
437119
8Largest Product in a Series
366603
9Special Pythagorean Triplet
371632
10Summation of Primes
340969
11Largest Product in a Grid
245191
12Highly Divisible Triangular Number
231740
13Large Sum
237038
14Longest Collatz Sequence
237432
15Lattice Paths
196250
16Power Digit Sum
239637
17Number Letter Counts
159499
18Maximum Path Sum I
152732
19Counting Sundays
141844
20Factorial Digit Sum
207543
21Amicable Numbers
154005
22Names Scores
141604
23Non-Abundant Sums
110380
24Lexicographic Permutations
121104
25$1000$-digit Fibonacci Number
163322
26Reciprocal Cycles
89281
27Quadratic Primes
92714
28Number Spiral Diagonals
113803
29Distinct Powers
111513
30Digit Fifth Powers
116039
31Coin Sums
90403
32Pandigital Products
75806
33Digit Cancelling Fractions
76150
34Digit Factorials
99584
35Circular Primes
89690
36Double-base Palindromes
93841
37Truncatable Primes
78070
38Pandigital Multiples
67042
39Integer Right Triangles
77614
40Champernowne's Constant
84740
41Pandigital Prime
72423
42Coded Triangle Numbers
78760
43Sub-string Divisibility
63773
44Pentagon Numbers
62415
45Triangular, Pentagonal, and Hexagonal
75105
46Goldbach's Other Conjecture
65581
47Distinct Primes Factors
61797
48Self Powers
117814
49Prime Permutations
61668
50Consecutive Prime Sum
66467