Using What You Know

Have you ever noticed that knowing just one simple fact can help you solve lots of problems? That’s exactly what we’re going to explore today. Let’s jump in!

The Power of One Simple Fact

Think about this math fact:

6 + 8 = 14

That’s pretty easy, right? You probably already knew that. But what if I told you that knowing this fact can help you add much bigger numbers in your head?

For example, let’s try:

56 + 8

Now, instead of solving this the hard way, let’s break it down:

• First, think of 56 as 50 + 6.
• Then, add 8 to 6. You already know 6 + 8 = 14.
• Now, put it back together: 50 + 14 = 64.

Boom! You got the answer without even writing it down.

Let’s try another one:

76 + 8

• Split 76 into 70 + 6.
• 6 + 8 is 14.
• Now, 70 + 14 equals 84.

See how simple that was?

Using the Strategy for Bigger Numbers

Now, what happens when there are zeros in the numbers? Guess what? The same trick works!

Let’s try 560 + 80:

• Break 560 into 500 + 60.
• You already know that 60 + 80 is just like 6 + 8 but with an extra zero: 140.
• So, 500 + 140 = 640.

Let’s do 760 + 80 together:

• Think of 760 as 700 + 60.
• 60 + 80 gives us 140 again.
• So, 700 + 140 = 840.

That’s it! The trick works every time.

Time to Practice!

Now, it’s your turn. Let’s try a few problems in your head. I’ll say the problem, and you try to solve it before I give the answer. Ready?

1. 47 + 5
Think: 40 + (7 + 5) → 40 + 12 = 52
Got it? Let’s try another!

2. 87 + 5
Think: 80 + (7 + 5) → 80 + 12 = 92

Now, let’s try one with zeros:

3. 470 + 50
Think: 400 + (70 + 50) → 400 + 120 = 520

Alright, last one:

4. 380 + 90
Think: 300 + (80 + 90) → 300 + 170 = 470

How did you do? If you got those right, give yourself a high-five! If you need more practice, rewind and try again.

This strategy is so powerful because it makes addition easy by breaking numbers into parts you already know. Instead of getting stuck on big numbers, you can work smarter, not harder!

Before we go, here’s a challenge: Try using this trick the next time you’re adding prices at a store or keeping track of points in a game. See how fast you can get!