Counting by Tens
Counting by tens means jumping by 10 each time instead of counting one by one. It is a fast way to count large groups of objects.
When we count by tens, we say: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.
What is Counting by Tens - Class 1 Maths (Numbers 10 to 20)?
Counting by tens (or skip counting by 10) means adding 10 each time to get the next number.
10 — 20 — 30 — 40 — 50 — 60 — 70 — 80 — 90 — 100
Each number in this list is 10 more than the one before. All these numbers end in 0.
Solved Examples
Example 1: Count by Tens to 50
Question: Count by tens from 10 to 50.
Think:
- Start at 10
- Add 10 each time: 10, 20, 30, 40, 50
Answer: 10, 20, 30, 40, 50.
Example 2: What Comes After 30?
Question: When counting by tens, what comes after 30?
Think:
- Add 10 to 30
- 30 + 10 = 40
Answer: 40 comes after 30.
Example 3: Counting Fingers
Question: 4 children hold up all their fingers. How many fingers in total?
Think:
- Each child has 10 fingers
- Count by tens: 10, 20, 30, 40
Answer: 40 fingers in total.
Example 4: Missing Number
Question: 10, 20, ___, 40, 50. What is the missing number?
Think:
- We are counting by tens
- After 20, add 10 → 30
Answer: The missing number is 30.
Example 5: How Many ₹10 Notes?
Question: Aman has ₹10 notes. He counts them: ₹10, ₹20, ₹30, ₹40, ₹50, ₹60. How many notes does he have?
Think:
- Each jump is one ₹10 note
- Count the jumps: 1, 2, 3, 4, 5, 6
Answer: Aman has 6 notes worth ₹60 in total.
Example 6: Count by Tens to 100
Question: Count by tens from 10 to 100.
Think:
- Keep adding 10 each time until you reach 100
10 — 20 — 30 — 40 — 50 — 60 — 70 — 80 — 90 — 100
Answer: There are 10 numbers in the count from 10 to 100 by tens.
Example 7: What Comes Before 70?
Question: When counting by tens, what comes just before 70?
Think:
- Subtract 10 from 70
- 70 − 10 = 60
Answer: 60 comes just before 70.
Key Points to Remember
- Counting by tens means adding 10 each time: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.
- Every number in this pattern ends in 0.
- Counting by tens is faster than counting one by one.
- There are 10 tens in 100.
- Useful when counting groups of 10 objects, like fingers or ₹10 notes.
Practice Problems
- Count by tens from 10 to 80.
- Fill in: 20, 30, ___, 50, ___.
- 5 children show all their fingers. Count by tens to find the total.
- How many tens make 100?
- Ria has 7 packets. Each packet has 10 biscuits. How many biscuits in all?
- Count backward by tens from 90 to 10.
Frequently Asked Questions
Q1. What is counting by tens?
Counting by tens means starting at 10 and adding 10 each time: 10, 20, 30, 40, 50, and so on up to 100.
Q2. Why do we count by tens?
Counting by tens is much faster when we have many objects grouped in sets of 10. Instead of counting 1, 2, 3, ... up to 50, we just say 10, 20, 30, 40, 50.
Q3. What do all numbers in the tens pattern have in common?
All of them end in 0. The ones digit is always 0.
Q4. How many tens are in 50?
There are 5 tens in 50, because 5 × 10 = 50.
Q5. Can I count by tens starting from a number other than 10?
Yes. For example, starting from 5 and counting by tens gives: 5, 15, 25, 35, 45. But in this lesson, we start from 10.
Q6. How many tens make 100?
10 tens make 100. Count: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 — that is 10 jumps of ten.
