Values, Types & Operators Exercises

Problem One

What are the types of the following expressions and what do they evaluate to, and why?

• 17 number 17 because its a number

• 1 + 2 * 3 + 4 numbers -> 1+6+4 -> 7+4 -> 11 it returns a value of 11

• 800 / 80 / 8 numbers because they're all numbers -> 10/8 -> 1.25

• 400 > 200 the type of expressions are boolean expressions -> true because 400 is greater than 200

• 1 !== 1 the type of expression is a boolean expression -> false this evaluated to false because 1 is equal to 1

• true || false the type of expression is a boolean expression -> true it is true because true is a truthy

• true && false this expression is a boolean expression ->false it is false because both sides are not truthy

• 20 % 6 this type is a number -> 2 because its a number

• 'a' + 'b' this expression type is a string ->'ab' because it has quotations

Problem Two

What will the following return?

• typeof 4 number
• typeof 'hello' string
• typeof true boolean
• 2 === 1 || 3 === 4 -> false

Problem Three

Create a truth table for the expression A || B.

For reference, here is a truth table for the expression A && B:

| A | B | A || B | |-------|-------|--------| | true | true | true | | false | true | true | | true | false | true | | false | false | false |

Problem Four

Create a truth table for the expression !A && !B.

For reference, here is a truth table for the expression A && !B:

A	B	!B	A && B
true	true	false	false
false	true	false	false
true	false	true	true
false	false	true	false

A	!A	B	!B	!A && !B
true	false	true	false	true
false	true	true	false	false
true	false	false	true	false
false	true	false	true	true

Problem Five

Create a truth table for the expression !(A || B).

| A | B | A || B |!(A || B)| |-------|-------|--------|-------- | | true | true | true | false | | false | true | false | true | | true | false | true | false | | false | false | false | true |

Problem Six

Write a step-by-step evaluation for the following expression (remember order of operations): 2 + 3 * 2 + 1. For reference, here is a exp of a step-by-step evaluation:

1 + 2 + 3 + 4  
    3 + 3 + 4
        6 + 4
            10
-> 2+6+1
-> 8+1
-> 9
-

Problem Seven

Write a step-by-step evaluation for the following expression (remember order of operations): 4 / 2 + 8 / 4. -> 2+2 -> 4

Problem Eight

Write a step-by-step evaluation for the following expression: 'ca' + 'ter' + 'pi' + 'llar'. -> "cater" + "pillar" -> "caterpilar"

Problem Nine

Write a step-by-step evaluation for the following expression: 2 * 4 === 8 && 'car' + 'pool' === 'carpool'.

-> 8 === 8 && 'car' + 'pool' === 'carpool'` -> 8 === 8 && 'carpool' === 'carpool' -> true && true -> true

Problem Ten

Write a step-by-step evaluation for the following expression: `'1' + '2' + '3'

• '1'`.

-> 3+3-1 -> 6-1 -> 5