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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
Advent calendar 2024
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List of all puzzles
Tags
area
star numbers
dodecagons
surds
square roots
shape
consecutive integers
crosswords
median
routes
balancing
numbers
unit fractions
coins
multiples
sums
rectangles
functions
digital clocks
people maths
perfect numbers
prime numbers
integration
chocolate
probabilty
ave
christmas
pentagons
hexagons
colouring
fractions
spheres
triangles
dominos
averages
regular shapes
sequences
cube numbers
books
factorials
grids
digital products
volume
algebra
decahedra
pascal's triangle
bases
medians
square grids
number
neighbours
the only crossnumber
cryptic clues
speed
range
lines
cards
perimeter
clocks
shapes
numbers grids
parabolas
polynomials
percentages
consecutive numbers
chess
doubling
games
differentiation
probability
geometric means
taxicab geometry
determinants
albgebra
menace
3d shapes
sets
triangle numbers
square numbers
coordinates
circles
geometric mean
quadrilaterals
factors
combinatorics
partitions
time
cryptic crossnumbers
digits
sum to infinity
wordplay
irreducible numbers
logic
proportion
folding tube maps
products
elections
even numbers
odd numbers
quadratics
expansions
gerrymandering
tournaments
angles
complex numbers
graphs
division
planes
binary
squares
floors
arrows
multiplication
sport
money
integers
polygons
powers
ellipses
calculus
trigonometry
indices
2d shapes
means
dates
symmetry
scales
geometry
axes
mean
matrices
tiling
cubics
dice
tangents
crossnumbers
advent
chalkdust crossnumber
rugby
addition
palindromes
remainders
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