Many programming languages have specific numeric types to represent different types of numbers, but JavaScript only has two:
number
: a numeric data type in the double-precision 64-bit floating-point format (IEEE 754).
Examples are -6
, -2.4
, 0
, 0.1
, 1
, 3.14
, 16.984025
, 25
, 976
, 1024.0
and 500000
.bigint
: a numeric data type that can represent integers in the arbitrary precision format.
Examples are -12n
, 0n
, 4n
, and 9007199254740991n
.If you require arbitrary precision or work with extremely large numbers, use the bigint
type.
Otherwise, the number
type is likely the better option.
There is a built-in global object called Math
that provides various rounding functions. For example, you can round down (floor
) or round up (ceil
) decimal numbers to the nearest whole numbers.
Math.floor(234.34); // => 234
Math.ceil(234.34); // => 235
JavaScript provides 6 different operators to perform basic arithmetic operations on numbers.
+
: The addition operator is used to find the sum of numbers.-
: The subtraction operator is used to find the difference between two numbers*
: The multiplication operator is used to find the product of two numbers./
: The division operator is used to divide two numbers.2 - 1.5; //=> 0.5
19 / 2; //=> 9.5
%
: The remainder operator is used to find the remainder of a division performed.
40 % 4; // => 0
-11 % 4; // => -3
**
: The exponentiation operator is used to raise a number to a power.
4 ** 3; // => 64
4 ** 1 / 2; // => 2
When using multiple operators in a line, JavaScript follows an order of precedence as shown in this precedence table. To simplify it to our context, JavaScript uses the PEDMAS (Parentheses, Exponents, Division/Multiplication, Addition/Subtraction) rule we've learnt in elementary math classes.
const result = 3 ** 3 + 9 * 4 / (3 - 1);
// => 3 ** 3 + 9 * 4/2
// => 27 + 9 * 4/2
// => 27 + 18
// => 45
Shorthand assignment operators are a shorter way of writing code conducting arithmetic operations on a variable, and assigning the new value to the same variable.
For example, consider two variables x
and y
.
Then, x += y
is same as x = x + y
.
Often, this is used with a number instead of a variable y
.
The 5 other operations can also be conducted in a similar style.
let x = 5;
x += 25; // x is now 30
let y = 31;
y %= 3; // y is now 1
In this exercise you will be writing code to help a freelancer communicate with their clients about the prices of certain projects. You will write a few utility functions to quickly calculate the costs for the clients.
A client contacts the freelancer to enquire about their rates. The freelancer explains that they work 8 hours a day. However, the freelancer knows only their hourly rates for the project. Help them estimate a day rate given an hourly rate.
dayRate(89);
// => 712
The day rate does not need to be rounded or changed to a "fixed" precision.
Another day, a project manager offers the freelancer to work on a project with a fixed budget. Given the fixed budget and the freelancer's hourly rate, help them calculate the number of days they would work until the budget is exhausted. The result must be rounded down to the nearest whole number.
daysInBudget(20000, 89);
// => 28
Often, the freelancer's clients hire them for projects spanning over multiple months.
In these cases, the freelancer decides to offer a discount for every full month, and the remaining days are billed at day rate.
Every month has 22 billable days.
Help them estimate their cost for such projects, given an hourly rate, the number of days the project spans, and a monthly discount rate.
The discount is always passed as a number, where 42%
becomes 0.42
. The result must be rounded up to the nearest whole number.
priceWithMonthlyDiscount(89, 230, 0.42);
// => 97972
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