Numbers Class 1 Notes Maths Chapter 11

Let's Understand the Number Ten

• Soniya and Pratham are neighbours.
• Pratham’s house number is 9 and Soniya’s house number is 10.
  Now, observe the following to understand the number 10 better.
  

10 is read as ten.

• Digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 stand-alone. So, they occupy only one place when written.
• Number 10 is made up of the digits 1 and 0. So, two places are needed to write 10.
  0 is written in Ones Place and 1 is written in a new place on the left of ones place.
  This new place is called the Tens Place. 
• Positions of 1 and 0 are fixed in the number 10.

Edurev Tips: 1, 2, 3, 4, 5, 6, 7, 8 and 9 are 1-digit numbers. 10 is the first 2-digit number.

10 ones make 1 ten

Let's learn about Numbers from 11 to 20

• The numbers from 11 to 19 are composed of one ten and one, two, three, four, five, six, seven, eight or nine ones respectively.
  

Edurev Tips: Number twenty is composed of 2 tens.

• Observe the following to understand the numbers from 11 to 20.
  

What comes Before, Between, and After a Number?

Read the conversation between Shiv and Amit.
Shiv: Today is my birthday and my cousin's birthday too. I am 7 years old and my cousin is 13 years old.
Amit: Congratulations to both of you! The numbers 8, 9, 10, 11, and 12 lie between 7 (your age) and 13 (your cousin's age).

Shiv: The number 14 comes just after 13 because it is next to 13 (or on the right of 13) in the number sequence. Also because 14 is 1 more than 13.

Amit: The number 12 comes just before 13 because it is on the left of 13 in the number sequence. Also because 12 is 1 less than 13.

Edurev Tips:

• To know a number just after the given number, we count one step forward.
• To know a number just before the given number, we count one step backward.

How to Compare the Numbers?

• '=' is the symbol used for 'equal to'.
• 3 = 3 is read as '3 is equal to 3'.
• Look at the numbers from 11 to 20 in order.
  The number 13 is to the left of 14. So, 13 < 14.
  The number 14 is to the right of 13. So, 14 > 13.
  Every number is equal to itself. 14 = 14, 15 = 15, 16 = 16, etc.

What are Ascending and Descending Orders?

There are 5 members in the Dubey family— Mr. Dubey, Ms. Dubey, Tina, Rahul, and their pet Rocky.

They are standing height-wise from the tallest to the shortest (in descending order) in picture 1 and from the shortest to the tallest (in ascending order) in picture 2.
In case of numbers:

• arranging or moving from the greatest number to the smallest number is called the descending order or decreasing order.
• arranging or moving from the smallest number to the greatest number is called the ascending order or increasing order. 

For example: The numbers 2, 4, 5, 8, and 9 are in ascending order whereas 9, 8, 5, 4, and 2 are in descending order.

Use of > or < in Forward and Backward Counting

• Jiya starts climbing the stairs from stair number 11. She has to reach stair number 20 to pick her pencil pouch that she dropped over there.
• As she goes up, she counts up (forward) as 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20. While coming back with her pencil pouch, she counts backward as 20, 19, 18, 17, 16, 15, 14, 13, 12, and 11.
• 11 < 12 < 13 < 14 < 15 < 16 < 17 < 18 < 19 < 20 is the ascending order of the numbers from 11 to 20. 20 > 19 > 18 > 17 > 16 > 15 > 14 > 13 > 12 > 11 is the descending order of the numbers from 20 to 11.

Edurev Tips: Numbers get “bigger/greater” when counting forward and “smaller/ lesser” when counting backwards.