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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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grids
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sequences
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graphs
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area
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surds
determinants
probabilty
volume
square grids
even numbers
dominos
spheres
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tiling
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multiplication
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division
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circles
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means
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cards
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range
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folding tube maps
regular shapes
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median
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colouring
cryptic crossnumbers
shape
dodecagons
matrices
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products
scales
tournaments
calculus
coins
consecutive integers
algebra
lists
partitions
integration
cube numbers
2d shapes
integers
clocks
digital products
proportion
triangle numbers
rugby
christmas
expansions
symmetry
medians
chocolate
geometry
angles
shapes
ave
perfect numbers
sum to infinity
digits
lines
probability
functions
chalkdust crossnumber
square roots
xor
numbers
percentages
multiplaction squares
powers
factors
planes
irreducible numbers
elections
prime numbers
mean
floors
complex numbers
books
crosswords
tangents
addition
sets
crossnumbers
coordinates
geometric mean
quadratics
advent
wordplay
cubics
number
decahedra
3d shapes
palindromes
the only crossnumber
square numbers
factorials
geometric means
remainders
speed
gerrymandering
taxicab geometry
albgebra
indices
unit fractions
people maths
sums
axes
routes
star numbers
binary
triangles
doubling
balancing
money
neighbours
dice
pentagons
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time
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