# 1.4 Scr0340: arithmetic operators in scratch 2.0  (Page 2/7)

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## Operands

According to the current jargon, operators operate on operands .

For example, in the following expression, the plus character is an operator while x and y are operands.

x + y

Assuming that x and y are numeric variables, this expression produces the sum of the values stored in the variables named x and y . The variable x would be called the left operand and the variable y would be called the right operand .

## Expressions

Computer programs in many languages consist of statements, which in turn, consist of expressions. (Programming blocks substitute for statements in Scratch.)

An expression is a specific combination of operators and operands that evaluates to a particular result. The operands can bevariables, literals, or method calls. (Note that Scratch v1.4 didn't support methods. However, Scratch 2.0 allows you to design and create yourown blocks, which helps to alleviate that deficiency.)

In your past experience, you may have referred to expressions by the names formulas or equations . Although formulas and equations are not exactly the same thing as expressions, they are close enough to help youunderstand what expressions are and how they are used.

## Statements

A statement is a specific combination of expressions. The following is an example of a statement comprised of expressions in a text-based language such as Java, C++,or C#.

z = x + y;

Operationally, values are retrieved from the variables named x and y in the above statement. These two values are added together. The result is stored in (assigned to) the variable named z , replacing whatever value may previously have been contained in that variable.

The plus character (+) would commonly be called the addition operator or the concatenation operator, depending on the type of data stored in the variables named x and y . The equal character (=) would commonly be called the assignment operator in Java, Alice, C#, and C++, but wewill see in a future module that it is also used as a relational operator in Scratch.

## A brief word about type

As a very crude analogy, you can think of variables as the pens at the animal shelter and think of type as the kinds of animals that reside in those pens. Dogs and cats aredifferent types of animals that don't usually coexist very well in the same pen. Therefore, they are normally put in different pens.

Similarly, different types of data don't coexist well in the same variable in type-sensitive languages. Therefore, in type-sensitive languages, there are very stringent rules as to the types of data that can be stored in each variable.

Scratch has two types of data that can be stored in a variable (numeric and string) . However, Scratch is not a type-sensitive language so type is not an issue in Scratch. (Scratch also has a semblance of a boolean type but it tends to take care of itself.)

## Unary, binary, and ternary operators

Many programming languages provide operators that can be used to perform an action on one, two, or three operands. I believe that operators in Scratchare confined to only one or two operands.

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
how did you get the value of 2000N.What calculations are needed to arrive at it
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