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