What is One Less Than 10?

S0-SA1-0748

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

One Less Than 10 means finding the number that comes just before 10 when you count backwards. It is the result of subtracting 1 from 10. This concept helps us understand how numbers relate to each other in sequence.

Simple Example

Quick Example

Imagine you have 10 ladoos in a box. If you eat one ladoo, how many are left? The number of ladoos remaining is one less than 10. So, 10 minus 1 gives you the answer.

Worked Example

Step-by-Step

Let's find out what is one less than 10 using a simple subtraction.

Step 1: Start with the number 10.
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Step 2: The phrase 'one less than' means we need to subtract 1 from the number.
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Step 3: Write down the subtraction problem: 10 - 1.
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Step 4: Count backwards one step from 10. If you count 10, 9, 8... the number just before 10 is 9.
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Step 5: Perform the subtraction: 10 - 1 = 9.

Answer: One less than 10 is 9.

Why It Matters

Understanding 'one less than' is fundamental for basic arithmetic and counting. It's crucial for everyday tasks like calculating change at a shop or keeping score in a game. It also lays the groundwork for advanced math concepts used by engineers, data scientists, and even astronauts at ISRO.

Common Mistakes

MISTAKE: Adding 1 instead of subtracting 1. Forgetting that 'less than' means subtraction. | CORRECTION: Always remember 'less than' implies taking away or subtracting. 'One less than X' means X - 1.

MISTAKE: Confusing 'one less than' with 'one more than'. | CORRECTION: 'One less than' means going down by one, while 'one more than' means going up by one. They are opposite operations.

MISTAKE: Getting stuck when the number is large, for example, 'one less than 100'. | CORRECTION: The rule remains the same no matter how big the number. Just subtract 1 from the given number.

Practice Questions

Try It Yourself

QUESTION: What is one less than 7? | ANSWER: 6

QUESTION: If you have 15 cricket balls and one ball rolls away, how many balls are left? This is 'one less than 15'. | ANSWER: 14

QUESTION: My grandmother is 60 years old. My grandfather is one year less than her age. How old is my grandfather? | ANSWER: 59

MCQ

Quick Quiz

Which number is one less than 10?

The Correct Answer Is:

One less than 10 means 10 minus 1, which equals 9. Options A, C, and D are incorrect as they represent one more than 10, 10 itself, or a completely different number, respectively.

Real World Connection

In the Real World

When you are shopping at a local kirana store and the shopkeeper gives you change, they often quickly calculate 'one less than' or 'one more than' to speed up the process. For example, if an item costs ₹9 and you give ₹10, they know the change is ₹1, which is one less than the amount you paid.

Key Vocabulary

Key Terms

LESS THAN: Smaller in quantity or amount | SUBTRACTION: The process of taking one number or quantity away from another | NUMBER LINE: A visual representation of numbers in order | COUNTING BACKWARDS: Reciting numbers in decreasing order | PREDECESSOR: The number that comes immediately before another number.

What's Next

What to Learn Next

Now that you understand 'one less than', you can explore 'one more than' a number. These concepts are building blocks for understanding addition and subtraction with larger numbers, which is essential for all future math topics.