Add Tens
Addition: Add Tens
Add Tens
Adding Two-Digit Numbers
NCERT anchor
Joyful Mathematics 2 — Add Our Points / Tens and Ones. Adding tens and ones separately connects directly to the tens-ones bundles used in these chapters.
What you'll learn
- To add two-digit numbers by adding ones to ones and tens to tens.
- To add multiples of ten quickly (20 + 30 = 50).
- To recognise when adding ones makes a new ten (regrouping) as a challenge step.
Key concepts
Verbal: Add the ones column first, then the tens column.
Symbolic: 24 + 35 → Ones: 4 + 5 = 9. Tens: 2 + 3 = 5. Answer: 59.
Level 1 — Adding round tens
20 + 30: think of 2 tens + 3 tens = 5 tens = 50.
Level 2 — Two-digit, no regrouping
34 + 22: ones 4+2=6, tens 3+2=5 → 56.
Level 3 — Two-digit, with regrouping (stretch)
27 + 15: ones 7+5=12 (write 2, carry 1 ten), tens 2+1+1=4 → 42.
Worked example
Find 24 + 35.
Step 1 — Add ones: 4 + 5 = 9
Step 2 — Add tens: 2 + 3 = 5
Answer: 59
Common mistakes
| Mistake | Why | Fix |
|---|---|---|
| Adding tens and ones together | Column mix-up | Line up tens under tens, ones under ones |
| Forgetting to carry the extra ten | New learners skip regrouping | If ones sum > 9, carry 1 ten to the tens column |
| Reading 24 + 35 as 2 + 4 + 3 + 5 | Ignoring place value | Each digit's place value matters |
Quick check
- 30 + 40 = ?
- 42 + 16 = ?
- 38 + 24 = ? (needs regrouping)
Stretch: Add 47 + 38 and check by adding in the reverse order.
Revision tip: Use bundles of ten sticks and loose ones to show why tens add with tens.
Open the Practice tab for graded questions on Adding Two-Digit Numbers.
Key Takeaways (TL;DR)
- NCERT anchor
- What you'll learn
- Key concepts
- Worked example
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