Lesson 6: Working with Numbers

Question 1

What are some Data Types?

Answer 1

• String
• Boolean true/false
• Null
• Undefined

Question 2

What are..

• Ox
• Ob
• Oo

Answer 2

Ox = Hexadecimal
Ob = Binary
Oo = Octal

Question 3

Show an example of Ox:

Answer 3

let x = oxff;

Question 4

Show an example of Ob:

Answer 4

let x = ob111;

Question 5

Show an example of Oo:

Answer 5

let x = oo777;

Question 6

What does toFixed do?

Answer 6

Returns a string with specified decimal places.

Question 7

What does the toString method do?

Answer 7

Converts a number into a string with the numerical base of the number.

Question 8

What are Number Objects used for?

Answer 8

To check and covert a numerical value.

Question 9

Number.isNaN(o/o):

Answer 9

Returns true.

Question 10

Number.isNaN(“abc”);

Answer 10

Returns false.

Question 11

What are the two values of Boolean type?

Answer 11

True or false.

Question 12

What does Null represent?

Answer 12

A valid but nonexistent value.

Question 13

What does Undefined indicate?

Answer 13

A variable has been declared but not assigned a value.

Question 14

What is an integer?

Answer 14

A whole number.

Question 15

What are Floating-Point numbers?

Answer 15

A number that contains a fractional part.

Question 16

What does the Number.isInteger() method do?

Answer 16

Determines whether a value or expression passed to it evaluates to an integer.

Question 17

What is the Number() function used for?

Answer 17

Getting numerical values from other data types.

Question 18

Number(true);

Answer 18

Returns 1.

Question 19

Number(false);

Answer 19

Returns 0.

Question 20

Number(‘horse’);

Answer 20

Returns NaN.

Question 21

Number(“666”);

Answer 21

Returns 666.

Question 22

What does the Negation Operator (!) mean?

Answer 22

Placed before a Boolean variable, means “the opposite value”.