DEV Community

Rawan Amr Abdulsattar
Rawan Amr Abdulsattar

Posted on • Originally published at codewithrona.blogspot.com

Javascript : Dealing with numbers

Javascript : #3 Dealing with numbers



In Javascript , you can do operations on numbers to help you do calculations and make things easier.


Basic operations on numbers

  • Addition : using " + " operator 
var sum ;

sum = 10 + 5 ;

console.log(sum); // output : 15
  • Subtraction : using " - " operator
var difference ;

difference = 22 - 10 ;

console.log(difference); // output : 12
  • Division : using " / " operator
var quotient ;

quotient = 50 / 5 ;

console.log(quotient); // output : 10
  • Multiplication : using " * " operator
var product ;

product = 7 * 2;

console.log(product); // output : 14
  • Getting remainder of division : using " % " operator
var remainder ;

remainder = 10 % 4;

console.log(remainder); // output : 2
  • Raising a number to a power : using the " ** " operator
var num = 3;

squaredNum = num ** 2;

console.log(squaredNum) // output : 9

Augmented operations on numbers

Sometimes , you want to update a variable storing a numeric value by doing any of the operations (like : adding to it , subtraction from it , dividing or multiplying it by something).class="javascript">But you don't have to use the long form like the following one.
var num = 2 ;

// adding 3 to the value of num and assigning this value (5) to the variable num

num = num + 3 ;

You can shorten it to be as the following example
var num = 2;

// adding 3 to the value of num and assigning this value (5) to the variable num

num += 3 ;

In the previous example , we used the plus equals operator " += "
which does the same thing as the code example before it.

This can be used in the operations (+, -, , /).

var num = 20 ;

// examples of augmented operations that can be done

num += 2 ;


num -= 3 ;

num *= 5 ;

num /= 11 ;


You can replace the value you use to update your variable by another variable as in the following example

var salary = 1500;

var bonus = 250;

console.log(salary); // output : 1500

salary += bonus;

console.log(salary); // output : 1750

Another example

var maxTemperature = 32;

var minTemperature = 24;

var averageTemperature = ( maxTemperature + minTemperature ) / 2 ;

console.log(averageTemperature); // output : 28


Incrementing and decrementing by one

Sometimes you want to update variables by incrementing or decrementing them by one, instead of using (num += 1 or num -= 1) , you can use a shorter way using " ++ " and " -- " operators./p>

var num = 6;

num++; // increases it by one to be 7

num--; // decreases it by one to be 6 again

Order of operations

If you have a more complex calculation you have to know what is calculated first , the order of operations that the computer follows is the same as the one you studied in your math's classes, which is PEDMAS (from left to right) :

  • Parenthesis (Brackets)
  • Exponents ( powers )
  • Division and Multiplication
  • Addition and Subtraction

Some people make it funnier and easier to remember by saying it like : " please excuse my dear aunt Sally ! "
Examplein ( 2 * (4 + 6) * 2 / 5 - 1) :
  • first ( 4 + 6 )  is calculated to be 10 , 
  • then it's raised to the second power to be 100 ,
  • then it's multiplied by 2 to be 200 , 
  • after that, it's divided by 5 to be 40 ,
  • and finally, 1 is subtracted from it to be 39.

Discussion (0)