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Problem Archives

The problems archives table shows problems 1 to 971. 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
1035956
2Even Fibonacci Numbers
823852
3Largest Prime Factor
593147
4Largest Palindrome Product
523651
5Smallest Multiple
525938
6Sum Square Difference
529660
710 001st Prime
452650
8Largest Product in a Series
379275
9Special Pythagorean Triplet
384422
10Summation of Primes
353316
11Largest Product in a Grid
253612
12Highly Divisible Triangular Number
240281
13Large Sum
245183
14Longest Collatz Sequence
245940
15Lattice Paths
203558
16Power Digit Sum
248077
17Number Letter Counts
165303
18Maximum Path Sum I
158372
19Counting Sundays
147009
20Factorial Digit Sum
214596
21Amicable Numbers
159664
22Names Scores
146625
23Non-Abundant Sums
115073
24Lexicographic Permutations
125750
25$1000$-digit Fibonacci Number
169333
26Reciprocal Cycles
93147
27Quadratic Primes
96636
28Number Spiral Diagonals
117920
29Distinct Powers
115852
30Digit Fifth Powers
120456
31Coin Sums
94352
32Pandigital Products
79218
33Digit Cancelling Fractions
79438
34Digit Factorials
103671
35Circular Primes
93429
36Double-base Palindromes
97489
37Truncatable Primes
81479
38Pandigital Multiples
69985
39Integer Right Triangles
80863
40Champernowne's Constant
88023
41Pandigital Prime
75634
42Coded Triangle Numbers
81854
43Sub-string Divisibility
66630
44Pentagon Numbers
65317
45Triangular, Pentagonal, and Hexagonal
78250
46Goldbach's Other Conjecture
68663
47Distinct Primes Factors
64639
48Self Powers
121945
49Prime Permutations
64461
50Consecutive Prime Sum
69542