What is One Less Than Ten?

S0-SA1-1120

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

One Less Than Ten refers to the number that comes just before ten when you count backwards. It means taking away one from the number ten. This concept helps us understand subtraction and number order.

Simple Example

Quick Example

Imagine you have 10 ladoos in a box. If you eat one ladoo, how many are left? You had 10, you took away 1, so now you have 9 ladoos remaining. So, one less than 10 is 9.

Worked Example

Step-by-Step

Let's find out what is one less than 10.

1. Start with the number 10.
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2. The phrase 'one less than' means we need to subtract 1 from this number.
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3. So, we write it as a subtraction problem: 10 - 1.
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4. Now, count backwards one step from 10. The number just before 10 is 9.
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5. Therefore, 10 - 1 = 9.

Answer: One less than ten is 9.

Why It Matters

Understanding 'one less than' is a basic step in learning subtraction, which is used everywhere! From managing money in a shop to calculating cricket scores or even coding simple programs, subtraction is key. This concept builds a strong foundation for future math topics and helps in careers like accounting, engineering, and data analysis.

Common Mistakes

MISTAKE: Students sometimes think 'one less than ten' means 1 and 10, or 1/10. | CORRECTION: 'One less than' always means subtraction. It's about finding the number that comes *before* the given number.

MISTAKE: Accidentally adding 1 instead of subtracting 1, getting 11. | CORRECTION: Remember 'less' means to reduce or take away. If it said 'one more than ten', then you would add 1.

MISTAKE: Confusing 'one less than' with 'one less digit'. | CORRECTION: 'One less than' refers to the numerical value, not the number of digits. 10 has two digits, but 9 (which is one less than 10) has only one digit.

Practice Questions

Try It Yourself

QUESTION: What is one less than 5? | ANSWER: 4

QUESTION: A bus had 12 passengers. If one passenger got off at the next stop, how many passengers are left? | ANSWER: 11 passengers

QUESTION: If you have 15 rupees and spend 1 rupee on a toffee, how much money do you have left? What is this an example of? | ANSWER: 14 rupees. This is an example of 'one less than 15'.

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. 11 is one more than 10, and 1 is a different number entirely.

Real World Connection

In the Real World

When you buy something at a small kirana store and the shopkeeper gives you change, they are often doing quick subtractions. For example, if an item costs ₹9 and you give ₹10, the shopkeeper quickly calculates 'one less than ten' to give you ₹1 back. This skill is useful in daily transactions, like using UPI where you quickly check if the amount is correct after a small deduction.

Key Vocabulary

Key Terms

LESS: To reduce or take away | SUBTRACTION: The process of taking one number or quantity away from another | NUMBER LINE: A straight line with numbers placed at equal intervals along its length | COUNTING BACKWARDS: Saying numbers in reverse order | PREDECESSOR: The number that comes immediately before a given number

What's Next

What to Learn Next

Great job understanding 'one less than'! Next, you can explore 'one more than' to see how numbers increase. Then, you can move on to 'two less than' or 'two more than' to build your subtraction and addition skills even further. Keep learning!