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Problems


IDDescription / TitleSolved By
1
Multiples of 3 and 5
294086
2
Even Fibonacci numbers
242454
3
Largest prime factor
176201
4
Largest palindrome product
161370
5
Smallest multiple
176269
6
Sum square difference
177830
7
10001st prime
151164
8
Largest product in a series
133567
9
Special Pythagorean triplet
133133
10
Summation of primes
121407
11
Largest product in a grid
91283
12
Highly divisible triangular number
81592
13
Large sum
88500
14
Longest Collatz sequence
86273
15
Lattice paths
71432
16
Power digit sum
92355
17
Number letter counts
59414
18
Maximum path sum I
59049
19
Counting Sundays
54047
20
Factorial digit sum
86541
21
Amicable numbers
58438
22
Names scores
54520
23
Non-abundant sums
40579
24
Lexicographic permutations
47583
25
1000-digit Fibonacci number
64653
26
Reciprocal cycles
33458
27
Quadratic primes
35372
28
Number spiral diagonals
48736
29
Distinct powers
42823
30
Digit fifth powers
45743
31
Coin sums
32922
32
Pandigital products
28604
33
Digit canceling fractions
30049
34
Digit factorials
40167
35
Circular primes
36757
36
Double-base palindromes
39492
37
Truncatable primes
30758
38
Pandigital multiples
26028
39
Integer right triangles
30271
40
Champernowne's constant
34109
41
Pandigital prime
28398
42
Coded triangle numbers
33234
43
Sub-string divisibility
23687
44
Pentagon numbers
22940
45
Triangular, pentagonal, and hexagonal
31594
46
Goldbach's other conjecture
24237
47
Distinct primes factors
23748
48
Self powers
54260
49
Prime permutations
23225
50
Consecutive prime sum
25081