Numbers From Ten to Twenty: Class 1 Maths NCERT

Understanding 'Ten' and Beyond

Before we jump into numbers like eleven or fifteen, let's understand the magical number ten. Imagine you have 10 yummy cookies. When we count from 1 to 9, each number represents a single item. But when we reach 10, something special happens! We can group these 10 cookies together and call it "one group of ten" or simply "one ten".

This idea of grouping items into tens is called place value, and it's super important. Once we have one group of ten, we can start adding more single items (which we call 'ones') to make new numbers. For example, if you have one group of ten cookies and then add 1 more cookie, you get eleven cookies! If you add 2 more cookies to your group of ten, you get twelve cookies. This pattern helps us build all the numbers from ten to twenty.

How to Form Numbers From Ten to Twenty

1. Number Ten (10) — When you have 10 single items (like 10 pencils), you can tie them together to make one bundle of ten. This is represented by the number 10. It has '1' in the tens place (meaning one bundle of ten) and '0' in the ones place (meaning zero loose items).
2. Number Eleven (11) — Take your bundle of ten pencils. Now, add 1 more loose pencil. You now have one bundle of ten and one loose pencil. This is the number 11. The first '1' means one ten, and the second '1' means one one.
3. Number Twelve (12) — Start with your bundle of ten. Add 2 loose pencils. You have one bundle of ten and two loose pencils. This is 12. The '1' is one ten, and the '2' is two ones.
4. Number Thirteen (13) to Nineteen (19) — You can continue this pattern! For Thirteen (13), it's one ten and three ones. For Fourteen (14), it's one ten and four ones. This continues all the way to Nineteen (19), which is one ten and nine ones. In each of these numbers, the '1' is in the tens place, showing one bundle of ten, and the second digit tells you how many loose ones you have.
5. Number Twenty (20) — What happens after nineteen? If you have one bundle of ten and nine loose pencils, and you add one more loose pencil, those 10 loose pencils can now become another bundle of ten! So, you now have two bundles of ten. This is the number 20. It has '2' in the tens place (meaning two bundles of ten) and '0' in the ones place (meaning zero loose items).

Counting and Writing Examples

• Example 1: Counting to Eleven Look at these stars: ⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐ ⭐ If you count them one by one, you'll see there are ten stars in the first group and one more star separately. So, altogether there are Eleven stars. We write this as 11.
• Example 2: Counting to Fifteen Imagine you have a box of 10 crayons and then 5 more crayons lying next to it. Box of Crayons: (10 crayons) Loose Crayons: 🖍️🖍️🖍️🖍️🖍️ If you count all of them, you have one group of ten and five ones. This makes Fifteen crayons. We write this as 15.
• Example 3: Counting to Eighteen Let's count dots: ●●●●●●●●●● ●●●●●●●● We have a group of 10 dots, and then another 8 dots. So, we have one ten and eight ones. This is Eighteen dots. We write this as 18.
• Example 4: Counting to Twenty Look at two rows of apples: 🍎🍎🍎🍎🍎🍎🍎🍎🍎🍎 🍎🍎🍎🍎🍎🍎🍎🍎🍎🍎 Each row has 10 apples. So, we have one group of ten and another group of ten. That makes two groups of ten, or Twenty apples. We write this as 20.

Important Things to Remember

• Numbers from 10 to 19 always start with the digit '1' in the tens place, which means 'one group of ten'.
• The second digit tells you how many 'ones' (loose items) are added to that group of ten.
• The number '20' means 'two groups of ten' and zero loose ones.
• Understanding 'tens' and 'ones' is the base for learning much bigger numbers later on. It's called place value!
• Practice counting forwards and backwards from 10 to 20 regularly.

Practice Questions with Solutions

• Q: Count the number of leaves shown below and write the number. 🍂🍂🍂🍂🍂🍂🍂🍂🍂🍂 🍂🍂🍂🍂 A: Step 1: Count the first group of leaves: There are 10 leaves. Step 2: Count the second group of leaves: There are 4 leaves. Step 3: Combine them: 1 group of ten and 4 ones. Final answer: The number is 14 (Fourteen).
• Q: Draw 17 small squares. How many tens and how many ones are there in 17? A: Step 1: Draw 10 squares in a row or group them. Step 2: Draw 7 more squares separately. Step 3: Identify the tens and ones. The number 17 has '1' in the tens place and '7' in the ones place. Final answer: 1 ten and 7 ones. (Drawing: [You would draw 10 squares and then 7 more])
• Q: What number comes just after 19? How many tens and ones does it have? A: Step 1: Count upwards from 19: 19, 20... Step 2: The number after 19 is 20. Step 3: Break down 20 into tens and ones. The number 20 has '2' in the tens place and '0' in the ones place. Final answer: 20 (Twenty). It has 2 tens and 0 ones.
• Q: Circle the number that represents 'one ten and six ones'. Options: 10, 16, 61, 6 A: Step 1: Understand 'one ten'. This means the first digit (tens place) should be 1. Step 2: Understand 'six ones'. This means the second digit (ones place) should be 6. Step 3: Combine these to form the number. Final answer: The number is 16.

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