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Advent calendar 2021
15 December
All 2021 advent puzzles
~
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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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List of all puzzles
Tags
digits
planes
consecutive integers
symmetry
shape
sets
wordplay
menace
shapes
polygons
sum to infinity
the only crossnumber
coins
2d shapes
binary
proportion
even numbers
combinatorics
parabolas
addition
factorials
differentiation
tangents
crosswords
factors
decahedra
routes
bases
speed
percentages
area
complex numbers
sums
christmas
cubics
rugby
star numbers
consecutive numbers
lines
calculus
regular shapes
median
multiplication
triangle numbers
prime numbers
dominos
crossnumbers
axes
games
averages
dodecagons
number
probabilty
gerrymandering
partitions
money
cryptic crossnumbers
ellipses
graphs
doubling
elections
perfect numbers
odd numbers
square numbers
scales
perimeter
integers
functions
fractions
colouring
triangles
pentagons
volume
time
quadratics
numbers
sport
algebra
square roots
books
surds
cube numbers
dice
squares
cryptic clues
geometric mean
3d shapes
probability
coordinates
spheres
crossnumber
grids
advent
indices
matrices
tiling
expansions
unit fractions
palindromes
geometry
folding tube maps
people maths
chocolate
cards
albgebra
division
pascal's triangle
dates
multiples
taxicab geometry
mean
digital products
ave
products
polynomials
floors
chess
integration
trigonometry
digital clocks
quadrilaterals
determinants
tournaments
rectangles
geometric means
means
circles
remainders
irreducible numbers
clocks
balancing
angles
chalkdust crossnumber
sequences
logic
range
arrows
hexagons
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