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Advent calendar 2015
17 December
All 2015 advent puzzles
~
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In March, I posted the puzzle
One Hundred Factorial
, which asked how many zeros 100! ends with.
What is the smallest number, n, such that n! ends with 50 zeros?
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205
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numbers
,
factorials
,
multiplication
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Most recent collections
Advent calendar 2025
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List of all puzzles
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albgebra
rectangles
range
gerrymandering
chess
balancing
time
lists
tiling
parabolas
coordinates
indices
chalkdust crossnumber
perimeter
angles
hexagons
averages
decahedra
determinants
cubics
trigonometry
3d shapes
functions
wordplay
volume
dodecagons
consecutive numbers
polygons
folding tube maps
expansions
odd numbers
partitions
lines
triangles
geometric means
surds
cryptic crossnumbers
crossnumbers
products
shape
consecutive integers
sequences
median
quadrilaterals
chocolate
cryptic clues
probabilty
symmetry
digital clocks
integration
ellipses
differentiation
menace
taxicab geometry
ave
rugby
doubling
remainders
squares
elections
medians
sum to infinity
neighbours
prime factors
circles
proportion
geometry
irreducible numbers
square numbers
clocks
geometric mean
games
colouring
digits
combinatorics
tangents
dominos
fractions
routes
square roots
digital products
star numbers
bases
probability
2d shapes
people maths
speed
binary
multiplaction squares
axes
sport
means
scales
powers
tournaments
xor
sums
graphs
planes
pascal's triangle
factors
addition
unit fractions
multiplication
books
spheres
floors
number
prime numbers
logic
grids
numbers
factorials
christmas
pentagons
cards
integers
palindromes
cube numbers
perfect numbers
regular shapes
sets
arrows
dates
matrices
money
multiples
mean
polynomials
crosswords
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triangle numbers
algebra
percentages
complex numbers
square grids
coins
area
even numbers
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dice
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