Mathematical headaches? Problem solved!
Hi, I'm Colin, and I'm here to help you make sense of maths
Written by Colin+ in podcasts.
Podcast: Play in new window | Download
Subscribe: Android | RSS
In this month's WBU spectacular:
WBUPuzzle solution: Alphabetically Begin Counting - Disregard Eight Forwards, Gale
Colin is a Weymouth maths tutor, author of several Maths For Dummies books and A-level maths guides. He started Flying Colours Maths in 2008.
He lives with an espresso pot and nothing to prove.
On shuffling. With 2N cards lable the cards from 0 to 2N-1 from bottom to the top of the pack. Suppose a perfect shuffle leaves 0 and 2N in place, moves 1 to 2, 2 to 4, … N to 1, N+1 to 3, …, 2N-1 to 2N-2. Ignoring the top card (which doesn’t move) each card, c, moves to 2c mod 2N-1. The number of shuffles to bring it back to the start is s where 2^s = 1 mod 2N-1.
Thre is an alternative riffle shuffle does move the top and bottom cards. Then we have 2^s = 1 mod 2N+1.
Is it as simple as that? I was under the impression that we didn’t know a lot about it yet. (Sadly, all my maths books are packed up at present so I can’t find where I got that from.)
I think I’d go with the ‘IN’ shuffle as an ‘Out’ shuffle can appear suspicious. Thanks for your comment.
Pingback: A nice little thought puzzle | cavmaths
On the first MathsJam, apparently everybody gave a talk. What percentage of the participants gave a talk at the zeroth MathsJam?
Your email address will not be published. Required fields are marked *
Notify me of follow-up comments by email.
Notify me of new posts by email.
This site uses Akismet to reduce spam. Learn how your comment data is processed.
Sign up for the Sum Comfort newsletter and get a free e-book of mathematical quotations.
No spam ever, obviously.
I teach in my home in Abbotsbury Road, Weymouth.
It's a 15-minute walk from Weymouth station, and it's on bus routes 3, 8 and X53. On-road parking is available nearby.
A Puzzle Full of Nines www.flyingcoloursmaths.co.uk/a…
September 28, 2020 9:00 am
He headed home after an abrupt 180. twitter.com/IMcMillan/status/1…
September 26, 2020 5:10 pm
Oh dear, Asda.
cc @standupmaths pic.twitter.com/voi2yPcxdc
September 26, 2020 5:06 pm
Some, uh, interesting maths in the cumulonumbers on Mary Hardy's dress here: www.dorchesterdorset.com/blog/…
When I next m… twitter.com/i/web/status/13098…
September 26, 2020 2:33 pm
“Yes, we’ve provided the brewery, and it’s branded as a piss-up, but we cannot currently accommodate any drinking." twitter.com/NHSCOVID19app/stat…
September 26, 2020 7:24 am