Search Problems   RSS Feed

Problem Archives

The problems archives table shows problems 1 to 1007. 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
847943
2Even Fibonacci Numbers
678474
3Largest Prime Factor
512066
4Largest Palindrome Product
452814
5Smallest Multiple
439292
6Sum Square Difference
444344
710 001st Prime
387281
8Largest Product in a Series
330230
9Special Pythagorean Triplet
335666
10Summation of Primes
315193
11Largest Product in a Grid
236530
12Highly Divisible Triangular Number
232876
13Large Sum
233660
14Longest Collatz Sequence
238037
15Lattice Paths
202113
16Power Digit Sum
236397
17Number Letter Counts
169685
18Maximum Path Sum I
164094
19Counting Sundays
153895
20Factorial Digit Sum
206992
21Amicable Numbers
169209
22Names Scores
155908
23Non-Abundant Sums
128774
24Lexicographic Permutations
137873
25$1000$-digit Fibonacci Number
175366
26Reciprocal Cycles
104904
27Quadratic Primes
108396
28Number Spiral Diagonals
127127
29Distinct Powers
128051
30Digit Fifth Powers
132934
31Coin Sums
104613
32Pandigital Products
89223
33Digit Cancelling Fractions
89117
34Digit Factorials
115276
35Circular Primes
103225
36Double-base Palindromes
107866
37Truncatable Primes
91197
38Pandigital Multiples
78363
39Integer Right Triangles
90158
40Champernowne's Constant
97135
41Pandigital Prime
84480
42Coded Triangle Numbers
90187
43Sub-string Divisibility
74531
44Pentagon Numbers
73051
45Triangular, Pentagonal, and Hexagonal
86578
46Goldbach's Other Conjecture
76613
47Distinct Primes Factors
72070
48Self Powers
123186
49Prime Permutations
71671
50Consecutive Prime Sum
76800