# Questions tagged [arithmetic]

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7k views

### Is there a virtue to learning how to compute by hand?

I have been professionally tutoring a wide range of students (from elementary school through graduate school) for many years. Most of them are from the United States. I generally focus on helping my ...
3k views

### Does this property of subtraction and division have a name?

Addition and multiplication are commutative. Denoting $\circ$ as either such operation, we have $$x \circ y = z \Leftrightarrow y \circ x = z.$$ Subtraction and division have a similar property, where ...
255 views

### Do electronic calculators inhibit mathematical thinking?

I am interested in educators real-world experience or being pointed to any research in this area. I have a student whose arithmetic skills are weak for his/her age. The student counts on his/her ...
2k views

### Different ways to multiply decimals

I am an undergraduate secondary math education major. In $2$ weeks I have to give a Number Talk in my math ed class on the problem "$3.9$ times $7.5$". I need to come up with as many different ...
1k views

### Why does the widespread erroneous definition of “irrational number” persist without being taught?

Among the mathematically ignorant one often finds a mistaken proposed definition of "irrational number", which says that it is a number whose decimal expansion does not terminate or repeat. The ...
6k views

### Is this primarily a “rote computational trick” for multiplication by 9?

I tried uploading a gif, but was unable to do so. What I can do, is share a link to the gif here. (SE software seems to have allowed me to share the link, but not upload it.) What it shows, ...
396 views

### What's the best technique to do math calculations in my head?

I wish to teach myself how to do math calculations–like $99\times 58$ or $2048+1296$ or $506+998$–inside my head. I know there already exist two methods–Abacus and Vedic Maths. I don't know of more, ...
180 views

### Generating system of equations with unique solutions

I have a similar problem addressed in System of Equations Generator. What I need is an automatic way of generating a system of equations with unique solutions, but the equations are not exclusively ...
159 views

### Learning operator priorities by drawing trees

As far as I know (and here I am refering to my own math education), operator priorities of $+$, $-$, $\cdot$, $\div$, power and paranthesis are taught via some simple phrases like "pointy" operators (...
2k views

### Adding things to bunches of things vs multiplication

"Suppose you bought four boxes of pencils having five pencils in each, how many pencils do you have altogether?" — "Nine." — "How come?" — "Because 4 plus 5 is 9." — "But you cannot add boxes to ...
529 views

### How to answer a three-year-old the question “Why is $2+6$ the same as $4+4$”?

I am teaching my daughter, who is currently about $46$ months old, additions. She is very curious and asks a lot of good questions. For example, when I told her that $2+6=8$ and $4+4=8$, she asked me ...
424 views

### Is there a numerical base that is in any way “better” for simple mathematical calculations than others?

I want to know if there are any numerical bases that are notably well-suited for humans to learn and use at an elementary or grade-school level. I know that different numerical bases (i.e. decimal/...
237 views

### What are other strategies for a 7 year old for addition and subtraction besides counting fingers?

We recently received feedback from our 7 year old daugther's school teacher. One of the things mentioned was that our daughter still counts her fingers when she does addition and subtraction. The ...
166 views

### Adding one to numbers bigger than ten

If someone asks you Tell me the next number (add one) after the number one million two hundred thirty-one thousand ninety-nine, do you known if it is a common error that the first number that ...
301 views

### How to explain the motivation of parentheses in addition, subtraction and multiplication?

My kid, 5 years old, knows addition, subtraction and multiplication now, of course, in a basic level. Also he understands that parentheses means "whichever inside shall be computed first". When I ...
406 views

### What’s better: number bonds, or addition tables?

I’ve been teaching my kids addition tables (1+3=4, 2+3=5, 3+3=6, etc.) I only just found out about number bonds (1+4=5, 2+3=5, 4+1=5). This seems a better method because it’s mastering all the ...
187 views

### Sensible amount of repetition 7 year old

We are now in lock-down, so while homeschooling my son I get to se exactly what he does for math. He has been getting a huge amount of repetitive practicing of really simple math, despite being quite ...
197 views

### Grading a Simple Rounding Exercise

A student is given the question: "Round off each of the following numbers, correct to two significant figures. 32.4892 8.2673 475.98 0.078625" There are two marks for each. If a student answers ...
236 views

### Looking for a video about arithmetic disappearing in a few years

I saw a video 3 or 4 years ago. The video is about the idea that arithmetic will disappear in the future and only will be a sport, like hunting that passed from a need to a sport. In the video there ...
289 views

### Concentrations of Adult Math Phobia

Some professions have more math phobia than others. Few engineers hate math, but many teachers and journalists do. This means that university departments of education and journalism would likely have ...
4k views

### Are soroban (Japanese abacus) classes worth doing?

The companies that run these expensive abacus programs for children claim it has all kinds of benefits for their mathematics abilities and speed. Apparently it starts with a child learning the ...
109 views

### Mental/“Paper and Pencil” Arithmetic

Recently, I was watching this video and I began thinking about how much my arithmetic skills have declined in recent years due to over reliance of calculators in upper year (high school) math courses. ...
297 views

### Logarithms chronologically before algebra

Do any textbooks or (somewhat?) standard curricula introduce logarithms and their applications in arithmetic without assuming the students know any algebra? (I do not mean just the use of logarithms ...