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Problem Archives

The problems archives table shows problems 1 to 987. 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
379196
9Special Pythagorean Triplet
384336
10Summation of Primes
353244
11Largest Product in a Grid
253576
12Highly Divisible Triangular Number
240239
13Large Sum
245136
14Longest Collatz Sequence
245892
15Lattice Paths
203533
16Power Digit Sum
248015
17Number Letter Counts
165329
18Maximum Path Sum I
158401
19Counting Sundays
147040
20Factorial Digit Sum
214554
21Amicable Numbers
159688
22Names Scores
146661
23Non-Abundant Sums
115128
24Lexicographic Permutations
125799
25$1000$-digit Fibonacci Number
169337
26Reciprocal Cycles
93261
27Quadratic Primes
96760
28Number Spiral Diagonals
118034
29Distinct Powers
115955
30Digit Fifth Powers
120561
31Coin Sums
94477
32Pandigital Products
79372
33Digit Cancelling Fractions
79608
34Digit Factorials
103793
35Circular Primes
93560
36Double-base Palindromes
97631
37Truncatable Primes
81623
38Pandigital Multiples
70143
39Integer Right Triangles
81027
40Champernowne's Constant
88176
41Pandigital Prime
75790
42Coded Triangle Numbers
82026
43Sub-string Divisibility
66798
44Pentagon Numbers
65480
45Triangular, Pentagonal, and Hexagonal
78435
46Goldbach's Other Conjecture
68831
47Distinct Primes Factors
64817
48Self Powers
122076
49Prime Permutations
64637
50Consecutive Prime Sum
69721