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Problem Archives

The problems archives table shows problems 1 to 913. If you would like to tackle the 10 most recently published problems, go to Recent problems.


ID

TitleSolved By
1Multiples of 3 or 5
1017236
2Even Fibonacci Numbers
810457
3Largest Prime Factor
583751
4Largest Palindrome Product
515947
5Smallest Multiple
518513
6Sum Square Difference
522049
7$10\,001$st Prime
446550
8Largest Product in a Series
374284
9Special Pythagorean Triplet
379456
10Summation of Primes
348414
11Largest Product in a Grid
250218
12Highly Divisible Triangular Number
236818
13Large Sum
241991
14Longest Collatz Sequence
242536
15Lattice Paths
200520
16Power Digit Sum
244730
17Number Letter Counts
162851
18Maximum Path Sum I
155957
19Counting Sundays
144794
20Factorial Digit Sum
211710
21Amicable Numbers
157248
22Names Scores
144482
23Non-Abundant Sums
112893
24Lexicographic Permutations
123625
25$1000$-digit Fibonacci Number
166757
26Reciprocal Cycles
91286
27Quadratic Primes
94733
28Number Spiral Diagonals
115964
29Distinct Powers
113839
30Digit Fifth Powers
118456
31Coin Sums
92442
32Pandigital Products
77579
33Digit Cancelling Fractions
77844
34Digit Factorials
101720
35Circular Primes
91627
36Double-base Palindromes
95757
37Truncatable Primes
79785
38Pandigital Multiples
68531
39Integer Right Triangles
79284
40Champernowne's Constant
86440
41Pandigital Prime
74073
42Coded Triangle Numbers
80333
43Sub-string Divisibility
65214
44Pentagon Numbers
63854
45Triangular, Pentagonal, and Hexagonal
76678
46Goldbach's Other Conjecture
67141
47Distinct Primes Factors
63212
48Self Powers
120070
49Prime Permutations
63046
50Consecutive Prime Sum
68027