Fun with Numbers (Numbers 21 to 99) Class 1 Notes Maths

Introduction

Number Names (21 to 99)

Place Value (Tens and Ones)

• In a two-digit number, the first digit represents the tens place, and the second digit represents the ones place.
• For example, in the number 56, 5 is in the tens place, and 6 is in the ones place.
• Understanding place value helps us read and write numbers correctly.

Counting (Skip Counting by Tens):

• We can count from 20 to 99 by adding 10 each time.
• For example, 20, 30, 40, 50, 60, 70, 80, 90.

Comparison of Numbers (Greater Than and Less Than):

• We can compare two two-digit numbers by looking at the digit in the tens place first.
• If the tens digits are different, the number with the greater tens digit is greater.
• If the tens digits are the same, we compare the ones digits to determine which number is greater.

21 to 30 - Let's Count

• Numbers 21 to 30 are formed by adding the tens place (20, 30) to the units place (1 to 10).
• For example, 21 is formed by adding 20 and 1, 22 is formed by adding 20 and 2, and so on.
• Practice counting from 21 to 30 to become familiar with these numbers.

31 to 40 - One More Ten

• Numbers 31 to 40 follow a similar pattern.
• They are formed by adding the tens place (30) to the units place (1 to 10).
• For example, 31 is formed by adding 30 and 1, 32 is formed by adding 30 and 2, and so on.
• Practice counting from 31 to 40 to get comfortable with these numbers.

41 to 50 - Moving Forward

• Numbers 41 to 50 are created by adding the tens place (40) to the units place (1 to 10).
• For example, 41 is formed by adding 40 and 1, 42 is formed by adding 40 and 2, and so on.
• Practice counting from 41 to 50 to reinforce your understanding.

51 to 60 - Climbing Higher

• Numbers 51 to 60 continue the pattern.
• They are formed by adding the tens place (50) to the units place (1 to 10).
• For example, 51 is formed by adding 50 and 1, 52 is formed by adding 50 and 2, and so on.
• Practice counting from 51 to 60 to become proficient with these numbers.

61 to 70 - A New Set

• Numbers 61 to 70 are formed by adding the tens place (60) to the units place (1 to 10).
• For example, 61 is formed by adding 60 and 1, 62 is formed by adding 60 and 2, and so on.
• Practice counting from 61 to 70 to strengthen your knowledge.

71 to 80 - Further Exploration

• Numbers 71 to 80 follow the same pattern.
• They are formed by adding the tens place (70) to the units place (1 to 10).
• For example, 71 is formed by adding 70 and 1, 72 is formed by adding 70 and 2, and so on.
• Practice counting from 71 to 80 to become more confident.

81 to 90 - Nearing the End

• Numbers 81 to 90 are created by adding the tens place (80) to the units place (1 to 10).
• For example, 81 is formed by adding 80 and 1, 82 is formed by adding 80 and 2, and so on.
• Practice counting from 81 to 90 to solidify your understanding.

91 to 99 - The Final Stretch

• Numbers 91 to 99 follow the same pattern as the previous sets.
• They are formed by adding the tens place (90) to the units place (1 to 9, as there is no 0 in the units place).
• For example, 91 is formed by adding 90 and 1, 92 is formed by adding 90 and 2, and so on.
• Practice counting from 91 to 99 to master these numbers.

What is the Ones and Tens Concept?

The number 10 is the first and the smallest two-digit number.

Example 1:

• Let’s take 10 pencils.

• Now make a group of 10 pencils.
• We can make only 1 group. It represents 1 Ten. But there is no single pencil remaining. It indicates 0 ones.
• So, the number 10 can write as:

Example 2:

• If we take 21 pencils, we can make 2 groups of 10 pencils that can be represented as 2 Tens.
• 1 remaining pencil can be represented as 1 Ones.

• 2 Tens and 1 Ones = 21
• We can write 21 as:

Example 3:

• We can represent 100 as 10 groups of Tens.
• We cannot write 100 as:
• We use the hundreds place. The number 100 is written as:

100 is the first and smallest three-digit number.

Missing Numbers