What is Ninety?

S0-SA1-0590

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Ninety is the natural number that comes right after 89 and right before 91. It is written as '90'. Ninety represents nine groups of ten things.

Simple Example

Quick Example

Imagine you are playing cricket and your favourite batsman has scored 89 runs. He needs just one more run to reach 90 runs! So, 90 is one more than 89.

Worked Example

Step-by-Step

Let's say you have 9 packets of biscuits, and each packet has 10 biscuits.
--- To find the total number of biscuits, you need to multiply the number of packets by the number of biscuits in each packet.
--- So, you calculate 9 packets × 10 biscuits/packet.
--- 9 × 10 = 90.
--- You have a total of 90 biscuits.

Why It Matters

Understanding numbers like 90 is super important for everyday life, from counting money to understanding scores in games. It helps in careers like banking, engineering, and even managing a small shop, where you constantly deal with quantities and calculations.

Common Mistakes

MISTAKE: Confusing 90 with 19 or 9. | CORRECTION: Remember that 90 has a '9' followed by a '0', meaning nine tens. 19 is one ten and nine ones, and 9 is just nine ones.

MISTAKE: Forgetting that 90 is an even number. | CORRECTION: An even number can be divided by 2 without any remainder. 90 divided by 2 is 45, so 90 is indeed an even number.

MISTAKE: Thinking 90 is a single-digit number. | CORRECTION: 90 is a two-digit number because it uses two digits (9 and 0) to represent its value.

Practice Questions

Try It Yourself

QUESTION: If you have 9 notes of 10 Rupees each, how much money do you have in total? | ANSWER: 90 Rupees

QUESTION: What number comes immediately after 89 and immediately before 91? | ANSWER: 90

QUESTION: A bus has 10 rows, and each row can seat 9 passengers. How many passengers can the bus carry in total? | ANSWER: 90 passengers

MCQ

Quick Quiz

Which of these statements about the number 90 is true?

It is a three-digit number.

It is an odd number.

It is equal to nine tens.

It comes before 89.

The Correct Answer Is:

90 is a two-digit number, not three. It is an even number, not odd. It comes after 89, not before. 90 is indeed nine groups of ten, making option C correct.

Real World Connection

In the Real World

When you buy groceries, the shopkeeper might tell you the total bill is 90 Rupees. Or, if you are looking at your mobile phone's battery, it might show 90% charge remaining, meaning it's almost full! Even in school, if you score 90 marks out of 100, that's an excellent score!

Key Vocabulary

Key Terms

DIGIT: A symbol used to write numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) | NATURAL NUMBER: Counting numbers starting from 1 (1, 2, 3...) | EVEN NUMBER: A number that can be divided by 2 without a remainder | PLACE VALUE: The value of a digit based on its position in a number (e.g., in 90, 9 is in the tens place)

What's Next

What to Learn Next

Great job understanding 90! Next, you can explore 'What is 100?' This will help you understand how numbers grow and how to count in hundreds, which is a big step in understanding larger numbers and place values.