Algorithmique du cycle 4 - 5e

Niveau 2 : variables

Exercice 1 : Déplacement véhicule - Décrémentation de variables (2/5)

Votre véhicule est équipé d'un réservoir contenant 20 litres d'essence, plein au démarrage, et il consomme de l'essence à chaque déplacement.

Nous allons modifier notre compteur pour qu'il diminue à chaque déplacement. Une variable peut être réutilisée pour faire un calcul avec sa valeur. Par exemple le bloc fournit la valeur actuellement mémorisée par la variable soustrait de 1. Combiné avec la balise , il est donc possible de modifier une variable en fonction de sa valeur précédente.

Modifier l'algorithme pour initialiser la variable et diminuer de 1 le niveau d'essence après chaque déplacement d'une case du véhicule.

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Exercice 2 : Comprendre les variables algorithmiques et mathématiques

Soit \(x\) un nombre réel.
Soit \(total\) un autre nombre réel, correspondant à la valeur renvoyée par l'algorithme.
\(total\) vaut \(x\) moins \(-2\) multiplié par \(-5\).

Compléter l'algorithme suivant afin qu'il réponde à l'énoncé.

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Si on entre un nombre \(x\) indiquer l'équation donnant \(total\).
Exemple de réponse : \(total = 0,01x + 1\)

Exercice 3 : Comprendre un algorithme d'inversion de valeurs (avec une 3e variable)

On considère l'algorithme ci-dessous :

\(C\) ← \(A\)
\(A\) ← \(B\)
\(B\) ← \(C\)

Quelles sont les valeurs en sortie de cet algorithme si l'on choisit \(A = 6\) et \(B= 19\) ?

Quelles sont les valeurs en sortie de cet algorithme si l'on choisit \(A = 1,7\) et \(B= 4,1\) ?

Exercice 4 : Initiation - Passer d'une instruction à une opération mathématiques

On considère l'algorithme ci-dessous :

Demander un nombre à l'utilisateur.
Ajouter 6
Multiplier par 2
Afficher le résultat

Si l'on note \(x\) le nombre fourni par l'utilisateur, donner l'expression du calcul réalisé par cet algorithme.

Exercice 5 : Afficher une table de multiplication (boucle et variables)

Écrire un algorithme qui permet d'afficher les tables de multiplications.
Le programme doit commencer par demander le nombre de la table à afficher puis les 10 valeurs de la tables (la multiplication de ce nombre par les nombres de 1 à 10 compris).
Par exemple si l'utilisateur rentre \(10\), le programme doit afficher :

\(10\)
\(20\)
\(30\)
\(40\)
\(50\)
\(60\)
\(70\)
\(80\)
\(90\)
\(100\)

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