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Problem Archives

The problems archives table shows problems 1 to 999. 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
856945
2Even Fibonacci Numbers
685017
3Largest Prime Factor
515930
4Largest Palindrome Product
456019
5Smallest Multiple
442448
6Sum Square Difference
447262
710 001st Prime
389872
8Largest Product in a Series
331865
9Special Pythagorean Triplet
337450
10Summation of Primes
316739
11Largest Product in a Grid
237133
12Highly Divisible Triangular Number
233447
13Large Sum
234195
14Longest Collatz Sequence
238570
15Lattice Paths
202341
16Power Digit Sum
236857
17Number Letter Counts
169699
18Maximum Path Sum I
164009
19Counting Sundays
153791
20Factorial Digit Sum
207006
21Amicable Numbers
169122
22Names Scores
155852
23Non-Abundant Sums
128456
24Lexicographic Permutations
137621
25$1000$-digit Fibonacci Number
175348
26Reciprocal Cycles
104595
27Quadratic Primes
108105
28Number Spiral Diagonals
126824
29Distinct Powers
127828
30Digit Fifth Powers
132585
31Coin Sums
104383
32Pandigital Products
88965
33Digit Cancelling Fractions
88803
34Digit Factorials
114959
35Circular Primes
102998
36Double-base Palindromes
107523
37Truncatable Primes
90930
38Pandigital Multiples
78150
39Integer Right Triangles
89875
40Champernowne's Constant
96941
41Pandigital Prime
84301
42Coded Triangle Numbers
89873
43Sub-string Divisibility
74279
44Pentagon Numbers
72848
45Triangular, Pentagonal, and Hexagonal
86310
46Goldbach's Other Conjecture
76399
47Distinct Primes Factors
71881
48Self Powers
123036
49Prime Permutations
71482
50Consecutive Prime Sum
76588