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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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3d shapes
quadratics
gerrymandering
multiples
time
hexagons
decahedra
unit fractions
parabolas
proportion
sums
powers
calculus
number
logic
taxicab geometry
money
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squares
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spheres
probability
grids
division
doubling
fractions
factors
chalkdust crossnumber
probabilty
digits
menace
dominos
chocolate
percentages
coins
mean
partitions
sport
clocks
expansions
angles
games
geometric mean
ellipses
2d shapes
albgebra
bases
people maths
wordplay
graphs
odd numbers
perimeter
crossnumbers
area
consecutive numbers
cryptic crossnumbers
polynomials
square numbers
numbers
trigonometry
determinants
prime numbers
geometry
functions
medians
triangle numbers
median
complex numbers
shape
perfect numbers
integers
numbers grids
multiplication
quadrilaterals
crosswords
palindromes
tournaments
combinatorics
square roots
folding tube maps
neighbours
means
remainders
surds
consecutive integers
dates
sum to infinity
routes
indices
rugby
sequences
star numbers
cube numbers
regular shapes
addition
products
dice
arrows
even numbers
digital products
matrices
floors
scales
circles
balancing
coordinates
tiling
the only crossnumber
elections
rectangles
sets
range
planes
cubics
pentagons
polygons
integration
digital clocks
symmetry
averages
differentiation
tangents
chess
binary
algebra
speed
cards
geometric means
pascal's triangle
volume
books
christmas
factorials
ave
cryptic clues
axes
triangles
colouring
irreducible numbers
lines
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