Numbers from 21 to 50 Chapter Notes | Mathematics Class 1 ICSE PDF Download

Introduction

What are the Numbers from 21 to 30?

The numbers from 21 to 29 are composed of two tens and one, two, three, four, five, six, seven, eight, or nine ones respectively.

Let us Read and Count the numbers from 21 to 30

• Let’s count forward from 21 to 30! These numbers come after 20 and help us count bigger groups of things—like balloons at a party, marbles in a jar, or steps in a staircase.
• As we move from 21 to 30, the numbers keep getting bigger. Let’s read them aloud and count them one by one. Are you ready? Let’s begin!

What are the Numbers from 31 to 40?

The numbers from 31 to 39 are composed of three tens and one, two, three, four, five, six, seven, eight, or nine ones respectively.

Let us Read and Count the numbers from 31 to 40

What are the Numbers from 41 to 50?

The numbers from 41 to 50 are composed of four tens and one, two, three, four, five, six, seven, eight, or nine ones respectively.

Let us Read and Count the numbers from 31 to 40

Twenties to Forties

• The Twenties
  Ms. Jones plays the piano very well. Playing the piano is her favourite pastime. She learned piano in her early twenties.
• The Thirties
  
• The Forties
  Kartik, Diwan, and their friends are rehearsing for a play on Independence Day.

Numbers on the Abacus

This is an abacus—a special tool used for counting and learning numbers. It has rods with beads that we can move back and forth to show different numbers.

Each spike or rod on the abacus represents a different place value:

• The rightmost rod stands for ones (1, 2, 3, …).
• The next rod stands for tens (10, 20, 30, …).
• More rods can show hundreds, thousands, and bigger numbers!

For example, to show the number 23, we move 2 beads in the tens place and 3 beads in the ones place. This helps us see how numbers are formed!

An abacus can be used for quick calculations.