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Problem Archives

The problems archives table shows problems 1 to 941. If you would like to tackle the 10 most recently published problems, go to Recent problems.


ID

TitleSolved By
1Multiples of 3 or 5
1031367
2Even Fibonacci Numbers
821078
3Largest Prime Factor
591531
4Largest Palindrome Product
522620
5Smallest Multiple
524995
6Sum Square Difference
528676
710 001st Prime
452013
8Largest Product in a Series
378860
9Special Pythagorean Triplet
384059
10Summation of Primes
352795
11Largest Product in a Grid
253292
12Highly Divisible Triangular Number
239959
13Large Sum
244961
14Longest Collatz Sequence
245641
15Lattice Paths
203141
16Power Digit Sum
247738
17Number Letter Counts
164925
18Maximum Path Sum I
157915
19Counting Sundays
146611
20Factorial Digit Sum
214259
21Amicable Numbers
159248
22Names Scores
146221
23Non-Abundant Sums
114486
24Lexicographic Permutations
125241
25$1000$-digit Fibonacci Number
168857
26Reciprocal Cycles
92554
27Quadratic Primes
96058
28Number Spiral Diagonals
117403
29Distinct Powers
115362
30Digit Fifth Powers
119962
31Coin Sums
93786
32Pandigital Products
78658
33Digit Cancelling Fractions
78938
34Digit Factorials
103128
35Circular Primes
92881
36Double-base Palindromes
97015
37Truncatable Primes
80932
38Pandigital Multiples
69491
39Integer Right Triangles
80358
40Champernowne's Constant
87585
41Pandigital Prime
75143
42Coded Triangle Numbers
81403
43Sub-string Divisibility
66148
44Pentagon Numbers
64835
45Triangular, Pentagonal, and Hexagonal
77760
46Goldbach's Other Conjecture
68168
47Distinct Primes Factors
64172
48Self Powers
121574
49Prime Permutations
63983
50Consecutive Prime Sum
69050