CBSE · Class 6-12

Class 9 · Ganita Manjari

Unit 11 · Class 9Ganita Manjari

The World of Algorithms

An algorithm is a step-by-step recipe. Explore ancient and modern algorithms for arithmetic and number theory.

Lessons

3 concepts

1
What Makes Something an Algorithm
A cake recipe is close to an algorithm — but only if every step is unambiguous. "Bake till golden" is subjective. In mathematics we insist every step has one, and only one, interpretation.
2
The Euclidean Algorithm — 2300 Years Old and Still Best
To find $\gcd(252, 105)$ : divide, take remainder, repeat. $252 = 2\cdot 105 + 42$ , $105 = 2\cdot 42 + 21$ , $42 = 2\cdot 21 + 0$ . HCF is the last non-zero remainder: $21$ . Nothing beats it for speed on large numbers.
3
Flowcharts and Sequential Thinking
Boxes for actions, diamonds for decisions, arrows for flow. A great way to plan any procedure — from solving an equation to designing an app.

Skills to practise

Skill · medium

The World of Algorithms — Practice