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Comments in green were written by me. Comments in blue were not written by me.
2019-12-17
@
Rob
: It looks to me like you've made mistakes in questions 1, 6, 8, and 9. The hints from the back of the pdf might help:
1.
How many numbers between 1 and 10,000 have 1 as their final digit? How many have 1 as their penultimate digit?
6.
How many ways can you write 1? 2? 3? 4? 5? What's the pattern?
8.
How many zeros does 10! end in? How many zeros does 20! end in? How many zeros does 30! end in?
9.
Carol’s sum is odd. What does this tell you about the 5- and 6-digit numbers?
Matthew
on
/blog/70
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Zines, pt. 2
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Dec 2023
Christmas card 2023
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Christmas (2023) is coming!
Zines
Sep 2023
TMiP 2023 puzzle hunt
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Chalkdust issue 17
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Logo Asteroids
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Mathsteroids on hyperbolic surfaces
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The databet
Jan 2023
Christmas (2022) is over
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Dec 2022
Off-by-one errors
Christmas card 2022
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Christmas (2022) is coming!
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24 Hour Maths Game Show
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Approximating π
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Build your own MENACE
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Christmas card 2021
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Christmas (2021) is coming!
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Close encounters of the second kind
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Christmas (2020) is coming!
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Happy ((gτ)-(π-√2))-58 Approximation Day!
May 2020
A surprising fact about quadrilaterals
Interesting tautologies
Mar 2020
Log-scaled axes
Feb 2020
PhD thesis, chapter ∞
PhD thesis, chapter 5
PhD thesis, chapter 4
PhD thesis, chapter 3
Inverting a matrix
PhD thesis, chapter 2
Jan 2020
PhD thesis, chapter 1
Gaussian elimination
Matrix multiplication
Christmas (2019) is over
2019
▼ show ▼
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Dec 2019
Visualising MENACE's learning
Christmas card 2019
Nov 2019
Christmas (2019) is coming!
Sep 2019
A non-converging LaTeX document
TMiP 2019 treasure punt
Jul 2019
Big Internet Math-Off stickers 2019
Jun 2019
Proving a conjecture
Apr 2019
Harriss and other spirals
Mar 2019
realhats
Jan 2019
Christmas (2018) is over
2018
▼ show ▼
▲ hide ▲
Dec 2018
Christmas cross stitch
MENACE in fiction
Christmas card 2018
Nov 2018
Christmas (2018) is coming!
Sep 2018
Runge's Phenomenon
Jul 2018
World Cup stickers 2018, pt. 3
Mathsteroids
Jun 2018
World Cup stickers 2018, pt. 2
May 2018
A bad Puzzle for Today
Apr 2018
Building MENACEs for other games
Mar 2018
A 20,000-to-1 baby?
World Cup stickers 2018
Jan 2018
Origins of World War I
Christmas (2017) is over
2017
▼ show ▼
▲ hide ▲
Dec 2017
Christmas card 2017
Nov 2017
Christmas (2017) is coming!
MENACE at Manchester Science Festival
Jun 2017
Big Ben Strikes Again
Mar 2017
The end of coins of constant width
Dragon curves II
Feb 2017
The importance of estimation error
Jan 2017
Is MEDUSA the new BODMAS?
2016
▼ show ▼
▲ hide ▲
Dec 2016
Christmas (2016) is over
Video game surfaces
Christmas card 2016
Nov 2016
Christmas (2016) is coming!
Oct 2016
Logical contradictions
Palindromic dates
Sep 2016
Tube map kaleidocycles
Jul 2016
Solving the cross diagonal cover problem
Jun 2016
Braiding, pt. 2
Braiding, pt. 1
Making names in Life
May 2016
Euro 2016 stickers
Mar 2016
Proving Pythagoras' theorem
Dragon curves
The
Mathematical Games
of Martin Gardner
Jan 2016
Christmas (2015) is over
2015
▼ show ▼
▲ hide ▲
Nov 2015
Christmas (2015) is coming!
Oct 2015
How to kick a conversion
How much will I win on the new National Lottery?
Aug 2015
How OEISbot works
MENACE
Mar 2015
Optimal Pac-Man
Tube map stellated rhombicuboctahedron
Logic bot, pt. 2
Design your own flexagon
Jan 2015
Tube map Platonic solids, pt. 3
2014
▼ show ▼
▲ hide ▲
Nov 2014
Logic bot
Sep 2014
Electromagnetic Field talk
Jun 2014
Tennis maths
May 2014
World Cup stickers
Apr 2014
Countdown probability, pt. 2
Countdown probability
Mar 2014
New machine unfriendly £1 coin, pt. 2
New machine unfriendly £1 coin
2013
▼ show ▼
▲ hide ▲
Dec 2013
Assorted christmaths
Pointless probability
Jul 2013
"Uncanny" royal coincidence
Raspberry Pi weather station
2012
▼ show ▼
▲ hide ▲
Nov 2012
Tube map Platonic solids, pt. 2
Oct 2012
Tube map Platonic solids
Tags
palindromes
realhats
light
exponential growth
matrix multiplication
hyperbolic surfaces
graphs
numerical analysis
radio 4
inverse matrices
anscombe's quartet
chebyshev
crossnumber
reddit
hannah fry
binary
inline code
guest posts
pi
world cup
people maths
go
data
matrix of cofactors
python
turtles
big internet math-off
fonts
london
flexagons
bubble bobble
hats
pascal's triangle
news
stirling numbers
bempp
christmas card
ucl
game of life
coins
talking maths in public
manchester
computational complexity
php
dragon curves
speed
dates
asteroids
phd
data visualisation
golden ratio
youtube
sorting
matrices
raspberry pi
matt parker
finite element method
latex
a gamut of games
braiding
squares
interpolation
wool
crochet
finite group
game show probability
newcastle
signorini conditions
errors
football
curvature
nine men's morris
logs
puzzles
tmip
mean
weak imposition
graph theory
matrix of minors
statistics
zines
stickers
hexapawn
estimation
preconditioning
london underground
dataset
simultaneous equations
sobolev spaces
cross stitch
geogebra
the aperiodical
polynomials
correlation
gerry anderson
fractals
live stream
menace
platonic solids
misleading statistics
ternary
triangles
cambridge
geometry
runge's phenomenon
plastic ratio
books
sport
gather town
quadrilaterals
approximation
logic
folding tube maps
draughts
logo
captain scarlet
weather station
error bars
royal baby
national lottery
harriss spiral
fence posts
boundary element methods
golden spiral
countdown
games
manchester science festival
mathsteroids
standard deviation
final fantasy
recursion
propositional calculus
chess
24 hour maths
machine learning
mathslogicbot
convergence
video games
edinburgh
datasaurus dozen
oeis
pythagoras
dinosaurs
noughts and crosses
frobel
databet
folding paper
gaussian elimination
tennis
pac-man
trigonometry
chalkdust magazine
determinants
craft
pizza cutting
martin gardner
arithmetic
programming
map projections
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rugby
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bodmas
pi approximation day
reuleaux polygons
probability
wave scattering
accuracy
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© Matthew Scroggs 2012–2024
1. How many numbers between 1 and 10,000 have 1 as their final digit? How many have 1 as their penultimate digit?
6. How many ways can you write 1? 2? 3? 4? 5? What's the pattern?
8. How many zeros does 10! end in? How many zeros does 20! end in? How many zeros does 30! end in?
9. Carol’s sum is odd. What does this tell you about the 5- and 6-digit numbers?
on /blog/70