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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
856724
2Even Fibonacci Numbers
684849
3Largest Prime Factor
515829
4Largest Palindrome Product
455946
5Smallest Multiple
442375
6Sum Square Difference
447193
710 001st Prime
389805
8Largest Product in a Series
331816
9Special Pythagorean Triplet
337398
10Summation of Primes
316691
11Largest Product in a Grid
237097
12Highly Divisible Triangular Number
233426
13Large Sum
234167
14Longest Collatz Sequence
238544
15Lattice Paths
202322
16Power Digit Sum
236835
17Number Letter Counts
169686
18Maximum Path Sum I
164004
19Counting Sundays
153785
20Factorial Digit Sum
206992
21Amicable Numbers
169116
22Names Scores
155850
23Non-Abundant Sums
128457
24Lexicographic Permutations
137618
25$1000$-digit Fibonacci Number
175338
26Reciprocal Cycles
104595
27Quadratic Primes
108106
28Number Spiral Diagonals
126824
29Distinct Powers
127829
30Digit Fifth Powers
132586
31Coin Sums
104384
32Pandigital Products
88966
33Digit Cancelling Fractions
88810
34Digit Factorials
114961
35Circular Primes
102999
36Double-base Palindromes
107528
37Truncatable Primes
90932
38Pandigital Multiples
78152
39Integer Right Triangles
89878
40Champernowne's Constant
96943
41Pandigital Prime
84301
42Coded Triangle Numbers
89875
43Sub-string Divisibility
74280
44Pentagon Numbers
72850
45Triangular, Pentagonal, and Hexagonal
86311
46Goldbach's Other Conjecture
76401
47Distinct Primes Factors
71881
48Self Powers
123038
49Prime Permutations
71484
50Consecutive Prime Sum
76587