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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
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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
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Christmas (2022) is over
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Off-by-one errors
Christmas card 2022
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Christmas (2022) is coming!
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Build your own MENACE
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Christmas (2021) is coming!
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Christmas (2020) is coming!
Jul 2020
Happy (√3-√2)+9 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!
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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
logo
edinburgh
speed
games
convergence
frobel
runge's phenomenon
advent calendar
flexagons
stirling numbers
youtube
matrix multiplication
arithmetic
matrix of minors
chalkdust magazine
european cup
nine men's morris
the aperiodical
harriss spiral
simultaneous equations
pi approximation day
programming
accuracy
pi
matrix of cofactors
chess
christmas
london underground
captain scarlet
python
geogebra
databet
data visualisation
weak imposition
christmas card
newcastle
gaussian elimination
misleading statistics
rugby
radio 4
fonts
finite element method
sound
statistics
fence posts
mean
javascript
24 hour maths
reuleaux polygons
folding tube maps
polynomials
dinosaurs
countdown
numerical analysis
data
weather station
hannah fry
national lottery
dates
asteroids
crossnumber
quadrilaterals
draughts
recursion
preconditioning
errors
mathsteroids
books
video games
bodmas
standard deviation
machine learning
php
logs
royal baby
cross stitch
go
news
sorting
light
dragon curves
logic
boundary element methods
error bars
people maths
determinants
puzzles
football
wave scattering
royal institution
curvature
binary
signorini conditions
probability
matt parker
inline code
craft
rhombicuboctahedron
trigonometry
map projections
sport
computational complexity
latex
guest posts
approximation
pythagoras
ucl
platonic solids
matrices
hats
sobolev spaces
cambridge
triangles
fractals
world cup
big internet math-off
talking maths in public
game of life
mathslogicbot
mathsjam
ternary
estimation
stickers
manchester science festival
graphs
menace
braiding
zines
hyperbolic surfaces
bubble bobble
wool
crochet
gather town
correlation
game show probability
realhats
graph theory
manchester
datasaurus dozen
bempp
a gamut of games
geometry
turtles
noughts and crosses
golden spiral
reddit
london
oeis
phd
anscombe's quartet
interpolation
hexapawn
folding paper
tmip
finite group
pascal's triangle
exponential growth
chebyshev
golden ratio
coins
palindromes
gerry anderson
squares
pizza cutting
pac-man
inverse matrices
dataset
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numbers
martin gardner
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live stream
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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