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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
×1
×1
×2
×1
×2
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Dec 2023
Christmas card 2023
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Christmas (2023) is coming!
Zines
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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
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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 (2020) is coming!
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Happy (3√2)+2 Approximation Day!
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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 ▼
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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
gerry anderson
talking maths in public
signorini conditions
palindromes
curvature
anscombe's quartet
crossnumber
misleading statistics
exponential growth
gaussian elimination
golden ratio
javascript
the aperiodical
gather town
flexagons
realhats
youtube
game of life
cambridge
reddit
binary
chebyshev
convergence
mathsteroids
video games
game show probability
sport
databet
books
christmas card
phd
edinburgh
tmip
determinants
radio 4
fractals
zines
geogebra
newcastle
coins
probability
boundary element methods
turtles
pi approximation day
geometry
hannah fry
dragon curves
hyperbolic surfaces
triangles
error bars
simultaneous equations
chess
pascal's triangle
live stream
manchester
manchester science festival
hats
finite group
sound
raspberry pi
numerical analysis
platonic solids
captain scarlet
dataset
harriss spiral
stickers
matrices
weak imposition
inline code
bempp
puzzles
guest posts
bubble bobble
fonts
hexapawn
data
sobolev spaces
wave scattering
standard deviation
plastic ratio
ucl
national lottery
logs
trigonometry
london underground
cross stitch
approximation
chalkdust magazine
statistics
interpolation
speed
european cup
royal baby
errors
braiding
asteroids
programming
matrix multiplication
latex
runge's phenomenon
pythagoras
light
mathslogicbot
logic
php
reuleaux polygons
data visualisation
big internet math-off
folding paper
dates
weather station
craft
accuracy
royal institution
electromagnetic field
logo
final fantasy
pi
wool
fence posts
map projections
advent calendar
frobel
numbers
world cup
propositional calculus
news
go
machine learning
graph theory
datasaurus dozen
polynomials
pac-man
matrix of cofactors
finite element method
draughts
pizza cutting
menace
rhombicuboctahedron
mean
folding tube maps
arithmetic
christmas
quadrilaterals
24 hour maths
matrix of minors
stirling numbers
rugby
estimation
games
sorting
a gamut of games
python
inverse matrices
martin gardner
noughts and crosses
recursion
london
people maths
mathsjam
graphs
oeis
dinosaurs
ternary
crochet
tennis
squares
matt parker
countdown
computational complexity
correlation
golden spiral
football
nine men's morris
bodmas
preconditioning
© 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