Speed Arithmetic
Return to my Mathematics pagesGo to my home page © Copyright 1998, Jim Loy Addition of two numbers: Let's add these two numbers in our heads (i.e., without paper). Memory is why speed arithmetic experts (I call them "arithmetickers") usually add numbers like these from left to right. Let's try again: 2+9=11, 1+3=4, 6+2=8, 6+7=3 and that previous 8 should have been a 9 (because of the carry). Addition of columns: How about this addition problem? In the right column, a speed arithmetic person might group the 9 and the 1 (10), the two 5's (10), and then the 7+2+4 (13) to get 33. Instead, what I do is add 29+37=66, then 66+15=81, then 81+21=102, 102+32=134, 134+85=219, and 219+44=263. Multiplication: 24 x48 ---- Speed arithmetic people multiply from left to right, too. 2x4 = 8 2x8 = 16 ---- 96 4x4 = 16 ---- 112 4x8 = 32 ---- 1152 See how that is done? Why? Why should a person learn to do this? Addendum (tricks): Older speed arithmetic books dwelt almost exclusively on tricks.
math online games for kids and children
The games is the doorway to Learning, Creativity and Self Discovery! The games is an main part of a child's development. It is also a central part of education and foundation of physical, social, emotional and mental health development. Test your memory as well as practice your math! Math game a flash card style game that displays random math problems in a variety of modes. The Math game application can be downloaded for use on either the windows or Macintosh operating system. You can use this software for training your or your kids math ability. Math is a simple program that, when used properly, will improve a child's basic math skills. Full version of software include the next features: Chart Multi users settings 4 elementary math action covering math with numbers, fractions, decimals Kids lock computer function Download Math right now or see web demo. Related articles
What’s Wrong with “Repeated Addition”? « Let's Play Math!
[Photo by Alejandra Mavroski.] Myrtle called it The article that launched a thousand posts…, and counting comments on this and several other blogs, that may not be too much of an exaggeration. Yet the discussion feels incomplete — I have not been able to put into words all that I want to say. Let me state up front that I speak as a teacher, not as a mathematician. I will start with a few things we can all agree on… We All Agree on Some Things Elementary students will use addition to solve beginning multiplication problems. So What’s the Problem? So what is wrong with the definition, “Multiplication is repeated addition”? To define multiplication as repeated addition is to make multiplication a sub-species of addition. It is as if there were two types of addition: regular, random, “wild” addition and the specially-bred variety of addition to which we give the name multiplication. The operation of addition has its identity element. And they are not the same. [Sidetrack: Oops! But… We need…
Visualizing Bayes’ theorem | Ramblings
I recently came up with what I think is an intuitive way to explain Bayes’ Theorem. I searched in google for a while and could not find any article that explains it in this particular way. Of course there’s the wikipedia page, that long article by Yudkowsky, and a bunch of other explanations and tutorials. But none of them have any pictures. Probabilities One of the easiest ways to understand probabilities is to think of them in terms of Venn Diagrams. So what is the probability that a randomly chosen person has cancer? Since A can have at most the same number of elements as U, the probability P(A) can be at most one. Good so far? So what is the probability that the test will be “positive” for a randomly selected person? Note that so far, we have treated the two events in isolation. We can compute the probability of both events occurring (AB is a shorthand for A∩B) in the same way. But this is where it starts to get interesting. So what is it? Which is Bayes’ theorem. Example
Free printable geometry worksheets
The worksheets below can be used as part of extra math homework. These geometry worksheets are free and easily printable. They cover typical school work from 4th through 8th grade. The printable worksheets are listed below by subject area. Lines, Shapes , and Objects Lines and Line Segments e.g. Area Angles Measuring Angles: Foundation - Identifying fractions of a circle Classifying Angles - acute, right, obtuse, etc. Triangles Types of Triangle e.g. scalene, isosceles, equilateral Similar Triangles (1 of 2) e.g. calculating scale factors and dimensions Similar Triangles (2 of 2) Pythagoras' Theorem Pythagorean Theorem (1 of 2) e.g. calculate the hypotenuse Pythagorean Theorem (2 of 2) e.g. calculate the opposite or adjacent Circles Symmetry Perimeter Volume Coordinate Geometry The Coordinate Graphing System - foundation questions about x and y-axes etc. Blank Grids Congruence and Similarity Congruent Triangles Transformations (Translations, Rotations, Reflections)
Free Multiplication Worksheets
Welcome to the multiplication facts worksheets page at Math-Drills.com! On this page, you will find Multiplication worksheets for practicing multiplication facts at various levels and in a variety of formats. This is our most popular page due to the wide variety of worksheets for multiplication available. Or it could be that learning multiplication facts and multiplication strategies are essential to many topics in mathematics beyond third grade math. We believe that learning the multiplication facts to the point of quick recall is a goal for all students. That's why we start you off with some multiplication tables, five minute frenzy charts and multiplication facts. Multiplication Tables Use the printable multiplication tables below to learn multiplication facts or the blank printable multiplication tables to practice multiplication facts. Five Minute Frenzy Charts Multiplication Facts to 49 Multiplication facts to 49 refer to any facts using the digits 0 to 7. Multiplication Facts to 81
