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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.
Carolâ€™s sum is odd. What does this tell you about the 5- and 6-digit numbers?
Matthew
on
/blog/70
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2021
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Christmas card 2020
Nov 2020
Christmas (2020) is coming!
Jul 2020
Happy τ+e-7 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
news
matrix of minors
hats
london
raspberry pi
folding paper
geometry
game of life
tennis
talking maths in public
speed
chess
frobel
convergence
mathsjam
flexagons
logic
logs
gaussian elimination
matt parker
rugby
rhombicuboctahedron
inline code
machine learning
royal baby
cambridge
world cup
coins
weak imposition
pizza cutting
stickers
sport
oeis
preconditioning
triangles
palindromes
boundary element methods
ternary
european cup
menace
approximation
bubble bobble
wool
braiding
weather station
golden ratio
reuleaux polygons
phd
martin gardner
sorting
interpolation
dates
binary
chebyshev
cross stitch
manchester science festival
captain scarlet
misleading statistics
matrices
pythagoras
books
computational complexity
bempp
exponential growth
football
people maths
gerry anderson
platonic solids
london underground
matrix of cofactors
mathslogicbot
php
harriss spiral
quadrilaterals
pi
big internet math-off
radio 4
determinants
advent calendar
propositional calculus
game show probability
graphs
pac-man
finite element method
noughts and crosses
tmip
dataset
dragon curves
plastic ratio
geogebra
javascript
accuracy
polynomials
go
python
signorini conditions
hannah fry
countdown
puzzles
nine men's morris
sound
trigonometry
mathsteroids
data
arithmetic
asteroids
simultaneous equations
programming
numerical analysis
statistics
latex
graph theory
national lottery
wave scattering
map projections
realhats
a gamut of games
games
probability
hexapawn
ucl
christmas card
draughts
bodmas
squares
golden spiral
the aperiodical
curvature
reddit
craft
inverse matrices
matrix multiplication
manchester
chalkdust magazine
video games
light
twitter
sobolev spaces
christmas
pi approximation day
electromagnetic field
royal institution
estimation
error bars
fractals
final fantasy
data visualisation
folding tube maps
© Matthew Scroggs 2012–2021

2019-12-171. 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. Carolâ€™s sum is odd. What does this tell you about the 5- and 6-digit numbers?

on /blog/70