Adding Double-Digit Numbers

🎯 What You'll Learn

You will learn to add two-digit numbers confidently, including adding tens to tens.

🏪 Market Story

Tunde goes to the market with ₦50. He buys garri for ₦20 and pure water for ₦30. He wonders: "How much did I spend?" He adds: ₦20 + ₦30 = ₦50. "Oh! I spent all my money!" he laughs.

📝 Let's Learn

When adding round tens numbers, just add the tens digits and put a zero at the end:

• ₦20 + ₦30: 2 tens + 3 tens = 5 tens = ₦50
• ₦40 + ₦50: 4 tens + 5 tens = 9 tens = ₦90

For non-round numbers, use partitioning:

Example 1: ₦35 + ₦24. Tens: 30 + 20 = 50. Ones: 5 + 4 = 9. Total: ₦59.

Example 2: ₦41 + ₦36. Tens: 40 + 30 = 70. Ones: 1 + 6 = 7. Total: ₦77.

Example 3: ₦52 + ₦25. Tens: 50 + 20 = 70. Ones: 2 + 5 = 7. Total: ₦77.

✏️ Practice Questions

1. ₦40 + ₦30 = ?
2. ₦23 + ₦45 = ?
3. Amina buys an exercise book for ₦32 and a pen for ₦15. How much does she spend?

Click to see answers

1. ₦40 + ₦30 = ₦70.
2. ₦23 + ₦45 = ₦68. Tens: 20 + 40 = 60. Ones: 3 + 5 = 8.
3. ₦32 + ₦15 = ₦47. Tens: 30 + 10 = 40. Ones: 2 + 5 = 7.

💡 Remember

When adding double-digit numbers, split into tens and ones, add each part, and combine. For round tens, just add the tens digits — it's fast and easy!