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Advent calendar 2021
15 December
All 2021 advent puzzles
~
More information
The odd numbers are written in a pyramid.
(row 1)
1
(row 2)
3
5
(row 3)
7
9
11
etc.
What is the mean of the numbers in the 19th row?
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The mean of the numbers in the \(n\)th row is \(n^2\), so the mean of the number in the 19th row is
361
.
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sum to infinity
cryptic crossnumbers
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people maths
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chalkdust crossnumber
probabilty
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geometric mean
rugby
hexagons
volume
irreducible numbers
squares
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the only crossnumber
crossnumbers
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surds
3d shapes
logic
multiples
averages
triangles
star numbers
crosswords
pentagons
combinatorics
elections
unit fractions
area
spheres
median
clocks
time
consecutive integers
determinants
factorials
binary
chess
cards
neighbours
differentiation
perfect numbers
lines
games
polynomials
scales
odd numbers
pascal's triangle
christmas
dominos
tiling
sport
expansions
lists
books
sets
cube numbers
parabolas
folding tube maps
prime factors
xor
taxicab geometry
partitions
number
fractions
dice
even numbers
algebra
triangle numbers
wordplay
indices
tangents
routes
ellipses
ave
speed
coins
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digital clocks
cubics
albgebra
coordinates
decahedra
tournaments
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