Search Problems   RSS Feed

Problem Archives

The problems archives table shows problems 1 to 1006. 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
848889
2Even Fibonacci Numbers
679168
3Largest Prime Factor
512484
4Largest Palindrome Product
453171
5Smallest Multiple
439648
6Sum Square Difference
444693
710 001st Prime
387545
8Largest Product in a Series
330416
9Special Pythagorean Triplet
335847
10Summation of Primes
315351
11Largest Product in a Grid
236619
12Highly Divisible Triangular Number
232948
13Large Sum
233727
14Longest Collatz Sequence
238116
15Lattice Paths
202161
16Power Digit Sum
236455
17Number Letter Counts
169694
18Maximum Path Sum I
164106
19Counting Sundays
153895
20Factorial Digit Sum
207015
21Amicable Numbers
169211
22Names Scores
155897
23Non-Abundant Sums
128757
24Lexicographic Permutations
137849
25$1000$-digit Fibonacci Number
175364
26Reciprocal Cycles
104875
27Quadratic Primes
108373
28Number Spiral Diagonals
127100
29Distinct Powers
128036
30Digit Fifth Powers
132901
31Coin Sums
104607
32Pandigital Products
89203
33Digit Cancelling Fractions
89092
34Digit Factorials
115255
35Circular Primes
103216
36Double-base Palindromes
107833
37Truncatable Primes
91182
38Pandigital Multiples
78347
39Integer Right Triangles
90136
40Champernowne's Constant
97136
41Pandigital Prime
84470
42Coded Triangle Numbers
90163
43Sub-string Divisibility
74503
44Pentagon Numbers
73030
45Triangular, Pentagonal, and Hexagonal
86554
46Goldbach's Other Conjecture
76595
47Distinct Primes Factors
72055
48Self Powers
123176
49Prime Permutations
71647
50Consecutive Prime Sum
76789