Knowledge of Everything

# Arithmetic

## Arithmetic or arithmetics (from the Greek word αριθμός = number) is the oldest and most elementary branch of mathematics

It is the method known as the “Method of the Indians” or in Latin “Modus Indoram” that has become our arithmetic today. Prior to this, basic arithmetic operations were highly complicated affairs. Seventh century Syriac Bishop Severus Sebhokt mentioned this method and stated that the method of the Indians is beyond description. Indian arithmetic was much simpler than the Greek arithmetic simply due to the simplicity of the Indian number system which had a zero and place value notation. Arabs learned this new method and called it “Hesab” or “Hindu Science”. Fibonacci or Leonardo of Pisa is one of the first European mathematicians who introduced the “Method of the Indians” to Europe. In his famous book “Liber Abaci” Fibonacci says that compared to this new method all other methods were mistakes.

Decimal arithmetic

Decimal notation constructs all real numbers from the basic digits, the first ten non-negative integers 0,1,2,…,9. A decimal numeral consists of a sequence of these basic digits, with the “denomination” of each digit depending on its position with respect to the decimal point: for example, 507.36 denotes 5 hundreds (102), plus 0 tens (101), plus 7 units (100), plus 3 tenths (10-1) plus 6 hundredths (10-2). An essential part of this notation (and a major stumbling block in achieving it) was conceiving of 0 as a number comparable to the other basic digits.

Algorism comprises all of the rules of performing arithmetic computations using a decimal system for representing numbers in which numbers written using ten symbols having the values 0 through 9 are combined using a place-value system (positional notation), where each symbol has ten times the weight of the one to its right. This notation allows the addition of arbitrary numbers by adding the digits in each place, which is accomplished with a 10 x 10 addition table. (A sum of digits which exceeds 9 must have its 10-digit carried to the next place leftward.) One can make a similar algorithm for multiplying arbitrary numbers because the set of denominations {…,102,10,1,10-1,…} is closed under multiplication. Subtraction and division are achieved by similar, though more complicated algorithms.

Arithmetic operations

The traditional arithmetic operations are addition, subtraction, multiplication and division, although more advanced operations (such as manipulations of percentages, square root, exponentiation, and logarithmic functions) are also sometimes included in this subject. Arithmetic is performed according to an order of operations. Any set of objects upon which all four operations of arithmetic can be performed (except division by zero), and wherein these four operations obey the usual laws, is called a field.

## Number theory

The term arithmetic is also used to refer to number theory. This includes the properties of integers related to primality, divisibility, and the solution of equations by integers, as well as modern research which is an outgrowth of this study. It is in this context that one runs across the fundamental theorem of arithmetic and arithmetic functions.

## Topics

 » Ackermann function » Addition » Additive inverse » Anomalous cancellation » Arithmetic » Arithmetic precision » Arithmetic rope » Casting out nines » Computer arithmetic » Division (mathematics) » Division algorithm » Elementary arithmetic » Empty product » Empty sum » Factorization » Finite field arithmetic » Fractions » Galley division » Hyper operator » Lecnac » List of basic arithmetic topics » Location arithmetic » Multiple (mathematics) » Multiplication » Peano axioms » Presburger arithmetic » Promptuary » Rabdology » Rounding » Shabakh » Significant figures » Subtraction » Subtraction without borrowing » Successor function » Sudan function » Summation » Swami Bharati Krishna Tirtha’s Vedic mathematics » Tetration » Trachtenberg system » Two plus two make five

#### More Arithmetic topics

 Arithmetic mean Arithmetic Presburger arithmetic Ordinal arithmetic Arithmetic lattice Arithmetic group Elementary arithmetic Philosophy of Arithmetic Arithmetic-geometric mean Arithmetic rope Affine arithmetic Non-standard arithmetic Arithmetic progression Arithmetic shift Arithmetic (song) Arithmetic coding Arithmetic precision Arithmetic function Arithmetic genus Arithmetic underflow Arithmetic overflow Treviso Arithmetic The Devil’s Arithmetic Verbal arithmetic Quasi-arithmetic mean Location arithmetic Roman arithmetic Robinson arithmetic Introduction to Arithmetic Saturation arithmetic Second-order arithmetic Heyting arithmetic Significance arithmetic Modular arithmetic Linear Arithmetic synthesis Primitive recursive arithmetic Reading, Writing, and Arithmetic Emotional Arithmetic (film) Fundamental theorem of arithmetic Fixed-point arithmetic Finite field arithmetic Arbitrary-precision arithmetic Arithmetic logic unit Arithmetic of abelian varieties Infinite arithmetic series Generalized arithmetic progression Hilbert’s arithmetic of ends Serial Number Arithmetic

## Multiplication table

× 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
2 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
3 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60
4 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80
5 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
6 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120
7 7 14 21 28 35 42 49 56 63 70 77 84 91 98 105 112 119 126 133 140
8 8 16 24 32 40 48 56 64 72 80 88 96 104 112 120 128 136 144 152 160
9 9 18 27 36 45 54 63 72 81 90 99 108 117 126 135 144 153 162 171 180
10 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
11 11 22 33 44 55 66 77 88 99 110 121 132 143 154 165 176 187 198 209 220
12 12 24 36 48 60 72 84 96 108 120 132 144 156 168 180 192 204 216 228 240
13 13 26 39 52 65 78 91 104 117 130 143 156 169 182 195 208 221 234 247 260
14 14 28 42 56 70 84 98 112 126 140 154 168 182 196 210 224 238 252 266 280
15 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 255 270 285 300
16 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 256 272 288 304 320
17 17 34 51 68 85 102 119 136 143 170 187 204 221 238 255 272 289 306 323 340
18 18 36 54 72 90 108 126 144 162 180 198 216 234 252 270 288 306 324 342 360
19 19 38 57 76 95 114 133 152 171 190 209 228 247 266 285 304 323 342 361 380
20 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400