Mental Addition: Doubles

🎯 What You'll Learn

You will learn the doubles addition facts and how to use "near doubles" to add quickly in your head.

🏪 Market Story

Chidi and his twin brother both get ₦7 as pocket money. Their mother asks, "How much do you two have together?" Chidi says, "That's double 7! 7 + 7 = ₦14." Then Funke gets ₦8. Chidi thinks, "8 is near 7. So 7 + 8 is like 7 + 7 plus 1 more. That's ₦15!"

📝 Let's Learn

Doubles are when you add a number to itself:

• 1 + 1 = 2
• 2 + 2 = 4
• 3 + 3 = 6
• 4 + 4 = 8
• 5 + 5 = 10
• 6 + 6 = 12
• 7 + 7 = 14
• 8 + 8 = 16
• 9 + 9 = 18
• 10 + 10 = 20

Near doubles: If you know 6 + 6 = 12, then 6 + 7 = 12 + 1 = 13.

Example 1: 8 + 8 = 16 (double 8).

Example 2: 8 + 9 = 8 + 8 + 1 = 16 + 1 = 17 (near double).

Example 3: 15 + 15 = 30 (double 15). So 15 + 16 = 30 + 1 = 31.

✏️ Practice Questions

1. What is 6 + 6?
2. Using doubles, what is 6 + 7?
3. What is 20 + 20? Then what is 20 + 21?

Click to see answers

1. 6 + 6 = 12.
2. 6 + 7 = 6 + 6 + 1 = 12 + 1 = 13.
3. 20 + 20 = 40. And 20 + 21 = 40 + 1 = 41.

💡 Remember

Memorise the doubles facts — they are your secret weapon! For near-doubles, just add 1 more to the doubles answer. Fast and simple!