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Problem Archives

The problems archives table shows problems 1 to 988. 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
1035781
2Even Fibonacci Numbers
823699
3Largest Prime Factor
593026
4Largest Palindrome Product
523515
5Smallest Multiple
525808
6Sum Square Difference
529544
710 001st Prime
452540
8Largest Product in a Series
379179
9Special Pythagorean Triplet
384318
10Summation of Primes
353223
11Largest Product in a Grid
253572
12Highly Divisible Triangular Number
240239
13Large Sum
245127
14Longest Collatz Sequence
245886
15Lattice Paths
203526
16Power Digit Sum
248002
17Number Letter Counts
165326
18Maximum Path Sum I
158401
19Counting Sundays
147038
20Factorial Digit Sum
214544
21Amicable Numbers
159685
22Names Scores
146656
23Non-Abundant Sums
115131
24Lexicographic Permutations
125800
25$1000$-digit Fibonacci Number
169331
26Reciprocal Cycles
93267
27Quadratic Primes
96765
28Number Spiral Diagonals
118051
29Distinct Powers
115957
30Digit Fifth Powers
120569
31Coin Sums
94482
32Pandigital Products
79382
33Digit Cancelling Fractions
79630
34Digit Factorials
103804
35Circular Primes
93573
36Double-base Palindromes
97641
37Truncatable Primes
81636
38Pandigital Multiples
70159
39Integer Right Triangles
81038
40Champernowne's Constant
88185
41Pandigital Prime
75803
42Coded Triangle Numbers
82035
43Sub-string Divisibility
66810
44Pentagon Numbers
65490
45Triangular, Pentagonal, and Hexagonal
78448
46Goldbach's Other Conjecture
68842
47Distinct Primes Factors
64824
48Self Powers
122080
49Prime Permutations
64653
50Consecutive Prime Sum
69733