Perfect numbers | Integer sequences
In number theory, a semiperfect number or pseudoperfect number is a natural number n that is equal to the sum of all or some of its proper divisors. A semiperfect number that is equal to the sum of all its proper divisors is a perfect number. The first few semiperfect numbers are: 6, 12, 18, 20, 24, 28, 30, 36, 40, ... (sequence in the OEIS) (Wikipedia).
Why aren't 51, 57, and 91 prime? They're semi-prime! Featuring @shane_duffy
I've talked before about my favorite "non-prime but seem like they should be prime numbers" and @shane_duffy asks here why some of them seem so…off-putting. The secret is that although they aren't prime, they are semi-prime. Semi-prime numbers are those numbers that have exactly two prime
From playlist polymathematic #shorts
Ex: Determine a Number that is Less Than and Greater than Using a Specific Place Value
This video provides examples of how to find a number that is less than and greater than a given number using a specific place value. Search Video Library at http://www.mathispower4u.wordpress.com
From playlist Whole Numbers: Place Value and Writing Numbers
Find the Closed Formula for a Sequence that is the Partial Sums of an Arithmetic Sequence
This video explains how to show that a repeating decimal is equal to a fraction. mathispower4u.com
From playlist Sequences (Discrete Math)
Conversion Arcs and 2,916,485,648,612,232,232,816 (MegaFavNumbers)
I'm sorry. The MegaFavNumbers playlist: https://www.youtube.com/playlist?list=PLar4u0v66vIodqt3KSZPsYyuULD5meoAo
From playlist MegaFavNumbers
Convert a Base-60 Number to Base-10 with a Decimal
This video explains how to convert a base sixty number to base ten with a decimal. http://mathispower4u.com
From playlist Historical Counting Systems
Given a Sequence, Find Partial Sums and Find a Formula For S_n Involving a_n
This video explains how to determine partial sums of a sequence. Then a formula is found for the sequence of partial sums involving a terms of the original sequence. mathispower4u.com
From playlist Sequences (Discrete Math)
This video covers the divisibility rules for 2,3,4,5,6,8,9,and 10. http://mathispower4u.yolasite.com/
From playlist Factors, Prime Factors, and Least Common Factors
#MegaFavNumbers What’s your Mega Favourite Number?
From playlist MegaFavNumbers
Ex: Division Using Partial Quotient - 4 Digit Divided by 2 Digit (No Remainder)
This video explains how to perform division using partial quotients. http://mathispower4u.com
From playlist Multiplying and Dividing Whole Numbers
How is i equal to square root of -1?
What is 'i'? More importantly, what is a complex number? How are complex numbers relevant to the context of other familiar numbers? Chapters: 00:00 Introduction 01:46 Logo of Reals and Rationals 02:11 Expanding real numbers 03:25 Motivation using whole (natural) numbers 06:08 Planar numb
From playlist Summer of Math Exposition 2 videos
Fun with Math: Surprises with Arithmetic and Numbers
Stephen Wolfram shows kids and adults some fun unique things you can do with math. All demonstrations powered by the Wolfram Language. Originally livestreamed at: https://twitch.tv/stephen_wolfram Follow us on our official social media channels: Twitter: https://twitter.com/WolframRese
From playlist Stephen Wolfram Livestreams
How to understand the REAL NUMBER LINE - COLLEGE ALGEBRA
In this video we talk about natural numbers, whole numbers, integers, rational numbers, irrational numbers, and real numbers. We also show the real number line and the inequalities less than and greater than. 00:00 Intro 00:29 Number system 04:53 Visual representation of numbers 07:37 Rea
From playlist College Algebra
This video provides a basic introduction into real numbers. It explains how to distinguish them from imaginary numbers. It also discusses the difference between rational and irrational numbers as well as integers, natural numbers, and whole numbers. Examples include repeating and non-re
From playlist New Algebra Playlist
This chemistry video tutorial answers the question - what are isotopes? Isotopes are substances that are composed of the same element but consist of different mass numbers and number of neutrons. They share the same atomic number and therefore the same number of protons. This video cont
From playlist New AP & General Chemistry Video Playlist
Pascal's wager and real numbers
My entry for 3blue1brown's contest, talking about Pascal's wager and how it leads to interesting questions about (hyper)real numbers. A big shoutout to Grant for coming up with this wonderful idea. Link to Thierry Platinis channel for more on hyperreal numbers: https://www.youtube.com/cha
From playlist Summer of Math Exposition Youtube Videos
Year 13/A2 Pure Chapter 0.1 (Subsets of Real Numbers, Representatives and Proof)
Welcome to the first video for year 13 (A2) Pure Mathematics! This video is part of a series of three that I've called Chapter 0, and is meant as a foundation for Year 13. The primary reasons for doing this are that the difficulty of Year 13 is markedly harder than Year 12 content, and al
From playlist Year 13/A2 Pure Mathematics
My favorite proof of the n choose k formula!
The binomial coefficient shows up in a lot of places, so the formula for n choose k is very important. In this video we give a cool combinatorial explanation of that formula! Challenge Problems playlist: https://www.youtube.com/playlist?list=PLug5ZIRrShJGkzGsXMYQt8bi5ImYtiEMM Subscribe t
From playlist Challenge Problems
Is the Sieve of Eratosthenese past its prime?
The Sieve of Eratosthenes is an amazing tool for teaching people about prime numbers and composite numbers but it's not without its limitations. I've tried to answer the question, 'Is there a better way of representing a sieve like this?' 0:00 Sieve of Eratosthenes In the first part of t
From playlist Summer of Math Exposition Youtube Videos
1,010,010,101,000,011 - #MegaFavNumbers
This is my submission to the #megafavnumbers project. My number is 1010010101000011, which is prime in bases 2, 3, 4, 5, 6 and 10. I've open-sourced my code: https://bitbucket.org/Bip901/multibase-primes Clarification: by "ignoring 1" I mean ignoring base 1, since this number cannot be fo
From playlist MegaFavNumbers
ALGEBRA & PRE-ALGEBRA REVIEW: Ch 1 (15 of 53) What Are Number Sets?
Visit http://ilectureonline.com for more math and science lectures! In this video I will explain what are counting numbers, whole numbers, integers, rational and irrational numbers, real numbers, and imaginary numbers. Next video in this series can be seen at: https://youtu.be/frXUlpNq4W
From playlist Michel van Biezen: MATH TO KNOW BEFORE HIGH SCHOOL