Elementary arithmetic is a branch of mathematics involving addition, subtraction, multiplication, and division. Due to its low level of abstraction, broad range of application, and position as the foundation of all mathematics, elementary arithmetic is generally the first branch of mathematics taught in schools.
See main article: Numeral system. In numeral systems, digits are characters used to represent the value of numbers. An example of a numeral system is the predominantly used Indo-Arabic numeral system (0 to 9), which uses a decimal positional notation.[1] Other numeral systems include the Kaktovik system (often used in the Eskimo-Aleut languages of Alaska, Canada, and Greenland), and is a vigesimal positional notation system.[2] Regardless of the numeral system used, the results of arithmetic operations are unaffected.
In elementary arithmetic, the successor of a natural number (including zero) is the next natural number and is the result of adding one to that number. The predecessor of a natural number (excluding zero) is the previous natural number and is the result of subtracting one from that number. For example, the successor of zero is one, and the predecessor of eleven is ten (
0+1=1
11-1=10
The natural numbers have a total ordering. If one number is greater than (
>
<
3<8
8>3
Counting assigns a natural number to each object in a set, starting with 1 for the first object and increasing by 1 for each subsequent object. The number of objects in the set is the count. This is also known as the cardinality of the set.
Counting can also be the process of tallying, the process of drawing a mark for each object in a set.
See main article: Addition. Addition is a mathematical operation that combines two or more numbers (called addends or summands) to produce a combined number (called the sum). The addition of two numbers is expressed with the plus sign (
+
When the sum of a pair of digits results in a two-digit number, the "tens" digit is referred to as the "carry digit". In elementary arithmetic, students typically learn to add whole numbers and may also learn about topics such as negative numbers and fractions.
See main article: Subtraction. Subtraction evaluates the difference between two numbers, where the minuend is the number being subtracted from, and the subtrahend is the number being subtracted. It is represented using the minus sign (
-
Subtraction is not commutative, which means that the order of the numbers can change the final value;
3-5
5-3
Subtraction is also used to separate, combine (e.g., find the size of a subset of a specific set), and find quantities in other contexts.
There are several methods to accomplish subtraction. The traditional mathematics method subtracts using methods suitable for hand calculation.[3] Reform mathematics is distinguished generally by the lack of preference for any specific technique, replaced by guiding students to invent their own methods of computation.
American schools teach a method of subtraction using borrowing.[4] A subtraction problem such as
86-39
70+16-39
The Austrian method, also known as the additions method, is taught in certain European countries. In contrast to the previous method, no borrowing is used, although there are crutches that vary according to certain countries.[6] [7] The method of addition involves augmenting the subtrahend. This transforms the previous problem into
(80+16)-(39+10)
Subtracting the numbers 792 and 308, starting with the ones column, 2 is smaller than 8. Using the borrowing method, 10 is borrowed from 90, reducing 90 to 80. This changes the problem to
12-8
| Hundreds | Tens | Ones | ||
| 8 | 12 | |||
| 7 | ||||
| − | 3 | 0 | 8 | |
| 4 |
In the tens column, the difference between 80 and 0 is 80.
| Hundreds | Tens | Ones | ||
| 8 | 12 | |||
| 7 | ||||
| − | 3 | 0 | 8 | |
| 8 | 4 |
In the hundreds column, the difference between 700 and 300 is 400.
| Hundreds | Tens | Ones | ||
| 8 | 12 | |||
| 7 | ||||
| − | 3 | 0 | 8 | |
| 4 | 8 | 4 |
The result:
792-308=484
See main article: Multiplication. Multiplication is a mathematical operation of repeated addition. When two numbers are multiplied, the resulting value is a product. The numbers being multiplied are multiplicands, multipliers, or factors. Multiplication can be expressed as "five times three equals fifteen", "five times three is fifteen" or "fifteen is the product of five and three".
Multiplication is represented using the multiplication sign (×), the asterisk (*), parentheses, or a dot (⋅). The statement "five times three equals fifteen" can be written as "
5 x 3=15
5\ast3=15
(5)(3)=15
5 ⋅ 3=15
In elementary arithmetic, multiplication satisfies the following properties:
a x b=b x a
a x (b x c)=(a x b) x c
a x (b+c)=a x b+a x c
In the multiplication algorithm, the "tens" digit of the product of a pair of digits is referred to as the "carry digit".
Multiplying 729 and 3, starting on the ones column, the product of 9 and 3 is 27. 7 is written under the ones column and 2 is written above the tens column as a carry digit.
| Hundreds | Tens | Ones | ||
| 2 | ||||
| 7 | 2 | 9 | ||
| × | 3 | |||
| 7 |
The product of 2 and 3 is 6, and the carry digit adds 2 to 6, so 8 is written under the tens column.
| Hundreds | Tens | Ones | ||
| 2 | ||||
| 7 | 2 | 9 | ||
| × | 3 | |||
| 8 | 7 |
The product of 7 and 3 is 21, and since this is the last digit, 2 will not be written as a carry digit, but instead beside 1.
| Hundreds | Tens | Ones | ||
| 2 | ||||
| 7 | 2 | 9 | ||
| × | 3 | |||
| 2 | 1 | 8 | 7 |
The result:
3 x 729=2187
Multiplying 789 and 345, starting with the ones column, the product of 789 and 5 is 3945.
| 7 | 8 | 9 | ||
| × | 3 | 4 | 5 | |
| 3 | 9 | 4 | 5 |
4 is in the tens digit. The multiplier is 40, not 4. The product of 789 and 40 is 31560.
| 7 | 8 | 9 | |||
| × | 3 | 4 | 5 | ||
| 3 | 9 | 4 | 5 | ||
| 3 | 1 | 5 | 6 | 0 |
3 is in the hundreds digit. The multiplier is 300. The product of 789 and 300 is 236700.
| 7 | 8 | 9 | ||||
| × | 3 | 4 | 5 | |||
| 3 | 9 | 4 | 5 | |||
| 3 | 1 | 5 | 6 | 0 | ||
| 2 | 3 | 6 | 7 | 0 | 0 |
Adding all the products,
| 7 | 8 | 9 | |||||
| × | 3 | 4 | 5 | ||||
| 3 | 9 | 4 | 5 | ||||
| 3 | 1 | 5 | 6 | 0 | |||
| + | 2 | 3 | 6 | 7 | 0 | 0 | |
| 2 | 7 | 2 | 2 | 0 | 5 |
The result:
789 x 345=272205
See main article: Division (mathematics) and Long division. Division is an arithmetic operation, and the inverse of multiplication. Given that
c x b=a
Division can be written as
a ÷ b
| ab | |
In some non-English-speaking cultures, "a divided by b" is written . In English usage, the colon is restricted to the concept of ratios ("a is to b").
In an equation
a ÷ b=c
Two numbers can be divided on paper using long division. An abbreviated version of long division, short division, can be used for smaller divisors.
A less systematic method involves the concept of chunking, involving subtracting more multiples from the partial remainder at each stage.
Dividing 272 and 8, starting with the hundreds digit, 2 is not divisible by 8. Add 20 and 7 to get 27. The largest number that the divisor of 8 can be multiplied by without exceeding 27 is 3, so it is written under the tens column. Subtracting 24 (the product of 3 and 8) from 27 gives 3 as the remainder.
| 2 | 7 | 2 | ||
| ÷ | 8 | |||
| 3 |
Going to the ones digit, the number is 2. Adding 30 (the remainder, 3, times 10) and 2 gets 32. The quotient of 32 and 8 is 4, which is written under the ones column.
| 2 | 7 | 2 | ||
| ÷ | 8 | |||
| 3 | 4 |
The result:
272 ÷ 8=34
Another method of dividing taught in some schools is the bus stop method, sometimes notated as result (divisor) dividend
The steps here are shown below, using the same example as above:
034 8|272 0 (8 × 0 = 0) 27 (2 - 0 = 2) 24 (8 × 3 = 24) 32 (27 - 24 = 3) 32 (8 × 4 = 32) 0 (32 - 32 = 0)The result:272 ÷ 8=34
Elementary arithmetic is typically taught at the primary or secondary school levels and is governed by local educational standards. In the United States and Canada, there has been debate about the content and methods used to teach elementary arithmetic.[8] [9]