Welcome, Young Mathematician! 🎉
You already know how to add single-digit numbers like 5 + 3 = 8. Now you’re ready for something more exciting – adding double-digit numbers! Don’t worry, it’s easier than you think.
What Are Double-Digit Numbers?
Double-digit numbers have two digits (two numbers side by side).
Examples: 12, 25, 43, 68, 91
- The digit on the left is called the TENS place
- The digit on the right is called the ONES place
Let’s Look at the Number 35:
- 3 is in the TENS place (it means 3 tens = 30)
- 5 is in the ONES place (it means 5 ones = 5)
- So 35 = 30 + 5
Method 1: Column Addition (The Traditional Way)
This is the most popular way to add double-digit numbers!
Steps:
- Write the numbers one below the other
- Line up the TENS and ONES columns
- Add the ONES column first (right side)
- Add the TENS column next (left side)
- Write your answer
Example 1: 23 + 14
TENS | ONES
2 | 3
+ 1 | 4
-----+-----
3 | 7
Step by step:
- Add ONES: 3 + 4 = 7 (Write 7 in the ones place)
- Add TENS: 2 + 1 = 3 (Write 3 in the tens place)
- Answer: 37
Example 2: 42 + 35
TENS | ONES
4 | 2
+ 3 | 5
-----+-----
7 | 7
Step by step:
- Add ONES: 2 + 5 = 7
- Add TENS: 4 + 3 = 7
- Answer: 77
Example 3: 51 + 26
TENS | ONES
5 | 1
+ 2 | 6
-----+-----
7 | 7
Step by step:
- Add ONES: 1 + 6 = 7
- Add TENS: 5 + 2 = 7
- Answer: 77
Method 2: Break Apart and Add (Expanded Form)
This method helps you understand WHAT you’re really adding!
Steps:
- Break each number into TENS and ONES
- Add all the TENS together
- Add all the ONES together
- Put them back together
Example 1: 23 + 14
Break apart:
- 23 = 20 + 3
- 14 = 10 + 4
Add the TENS: 20 + 10 = 30
Add the ONES: 3 + 4 = 7
Put together: 30 + 7 = 37
Example 2: 42 + 35
Break apart:
- 42 = 40 + 2
- 35 = 30 + 5
Add the TENS: 40 + 30 = 70
Add the ONES: 2 + 5 = 7
Put together: 70 + 7 = 77
Example 3: 61 + 12
Break apart:
- 61 = 60 + 1
- 12 = 10 + 2
Add the TENS: 60 + 10 = 70
Add the ONES: 1 + 2 = 3
Put together: 70 + 3 = 73
Method 3: Using a Number Line (Jump and Hop!)
This is a fun visual way to add!
Steps:
- Start at the first number
- Jump forward by the TENS of the second number
- Hop forward by the ONES of the second number
- See where you land!
Example: 32 + 25
Start at 32
Jump by 20 (the tens in 25): 32 → 42 → 52 (We jumped by 10 twice!)
Hop by 5 (the ones in 25): 52 → 53 → 54 → 55 → 56 → 57
Answer: 57
Example: 23 + 14
Start at 23
Jump by 10: 23 → 33
Hop by 4: 33 → 34 → 35 → 36 → 37
Answer: 37
Tips and Tricks 💡
Tip 1: Always Start with the ONES
When using column addition, ALWAYS add the ones column first (the right side). This is a good habit that will help you later!
Tip 2: Line Up Your Numbers
Make sure your numbers are written neatly, with TENS under TENS and ONES under ONES. Use grid paper if it helps!
Tip 3: Check Your Answer
You can check if your answer is correct by switching the numbers around:
- If 23 + 14 = 37, then 14 + 23 should also = 37
Tip 4: Use Your Fingers
If you’re stuck on the ONES addition (like 3 + 4), it’s okay to use your fingers! Count 3 fingers, then count 4 more. How many do you have?
Tip 5: Think About TENS First
When adding 42 + 35, think: “I have 4 tens and 3 tens = 7 tens = 70, then I have 2 ones and 5 ones = 7 ones.” Put them together: 70 + 7 = 77!
Tip 6: Draw It Out
Draw boxes or sticks to represent tens and dots for ones. For 23 + 14:
- Draw 2 boxes and 3 dots (for 23)
- Draw 1 box and 4 dots (for 14)
- Count them all: 3 boxes = 30, and 7 dots = 7, so 30 + 7 = 37
Tip 7: Practice Makes Perfect
The more you practice, the faster you’ll become! Try to do a few problems every day.
Remember:
✓ Break numbers into TENS and ONES
✓ Add ONES first, then TENS
✓ Line up your numbers carefully
✓ Practice makes you better every day!
You’re doing great! Keep practicing and soon you’ll be an addition expert! 🌟
