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Recap - Sum of Even Numbers

Part of the Fundamentals section of Coddy's Lua journey — lesson 90 of 90.

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Challenge

Easy

Write a script that calculates the sum of all even numbers from 1 to 20 using a for loop, conditional logic, and variable accumulation.

Create a local variable named total and initialize it to 0. Then use a numeric for loop to iterate through all numbers from 1 to 20.

Inside the loop:

  • Use the modulo operator (%) to check if the current number is even
  • If the number is even, add it to your running total

After the loop completes, print the final sum of all even numbers.

Try it yourself

-- Initialize the total variable
local total = 0

-- TODO: Write your code here
-- Use a for loop to iterate from 1 to 20
-- Check if each number is even using the modulo operator (%)
-- Add even numbers to the total

-- Output the result
print(total)

All lessons in Fundamentals

1Introduction

The LanguageHello World!Comments

4Operators 2 Relational & Logic

Equality OperatorsRelational OperatorsThe 'and' OperatorThe 'or' OperatorThe 'not' OperatorShort-Circuit EvaluationTruthy and Falsy ValuesRecap - Simple Logic

7Basic Conditional Logic

The if-then StatementThe if-then-else StatementThe elseif StatementRecap - Treasure Chest

10Tables Part 1: List-Style

What is a Table?Creating a TableAccessing Elements by IndexModifying Elements by IndexThe Length Operator '#'table.insert()table.remove()Recap - Manage Party Members

13Project: Simple Potion Shop

Project SetupAdding a PotionProject lessonDisplaying the InventoryProject lessonCalculating Total Stock ValueProject lessonFinding a Specific PotionProject lessonSelling a PotionProject lesson

2Variables and Data Types

What is a Variable?NumbersStringsBooleansThe Value 'nil'The type() FunctionNaming ConventionsRecap - Character Profile

5Basic Output

Printing LiteralsPrinting VariablesPrinting Multiple ValuesCombining Strings & VariablesThe tostring() FunctionInputCastRecap - Status ReportRecap - Till 120

8String Manipulation Basics

string.len()string.upper & string.lowerstring.sub()string.rep()string.find()Recap - Format Username

11Tables 2: Dictionary-Style

Key-Value PairsCreating Dictionary-Style TablAccessing - Bracket NotationAccessing with Dot NotationAdding and Modifying PairsRemoving Pairs with nilRecap - Item Properties

14Variable Scope

Global VariablesLocal VariablesWhy Use Local Variables?Scope and BlocksRecap - Scope Puzzle

3Operators 1 Arithmetic & Conc

Arithmetic OperatorsModulo OperatorExponentiation OperatorString ConcatenationOperator PrecedenceRecap - Simple Calculations

6Project: Character Stats Disp

Welcome MessageDeclare Character StatsProject lessonDisplay Basic StatsProject lessonAdd a Boolean FlagProject lessonFinal SummaryProject lesson

9Functions Basics

Declaring a FunctionCalling a FunctionFunctions with ParametersFunctions with Multiple ParamsThe 'return' StatementRecap - Area Calculator

12Loops Basics

The while LoopThe repeat-until LoopThe Numeric for Loopfor Loop with a StepThe 'break' StatementRecap - Countdown

15Final Challenges

Recap - Player TurnRecap - Simple DatabaseRecap - Sum of Even Numbers