Using Compensation to Add Numbers:
39 + 7
Understanding compensation can make adding numbers easier! Let’s take a look at how we can use compensation to solve 39 + 7 step by step.
What is Compensation?
Compensation is a math trick that helps us make addition easier by adjusting the numbers. We can change the numbers in a way that makes them simpler to add, and then fix the change at the end. It’s like rounding the numbers up or down, but making sure we correct it after!
Let’s Solve 39 + 7 Using Compensation
- Step 1: Make it Easier
- We start with 39 + 7. But adding 39 + 7 isn’t as easy as adding 39 + 10, right? So, let’s add a bit to 7 to make it 10.
- 39 + 7 becomes 39 + 10, but we’ve added 3 extra to the 7.
- Step 2: Fix the Extra
- Since we added 3 extra, we need to take it back. So, we subtract 3 from our new sum.
- First, let’s do the addition: 39 + 10 = 49.
- Now, subtract 3 from 49: 49 – 3 = 46.
The Final Answer: 39 + 7 = 46
We’ve used compensation to make the addition easier! Here’s how it looks:
39 + 7 = 39 + 10 – 3
Why Does This Work?
Compensation works because we added a number that made the calculation simpler. Then, we subtracted the extra part that we added to fix our answer. This helps you see that you can break down tricky problems into easier parts!
Quiz:
1) Fill in the missing numbers to find 78 + 7
| 78 | + | 7 | = | (78 | + | 10) | – | |
| 78 | + | 7 | = |
2) Fill in the missing numbers to find 36 + 9
| 36 | + | 9 | = | (36 | + | 10) | – | |
| 36 | + | 9 | = |
3) Fill in the missing numbers to find 87 + 7
| 87 | + | 7 | = | (87 | + | 10) | – | |
| 87 | + | 7 | = |
4) Fill in the missing numbers to find 75 + 7
| 75 | + | 7 | = | (75 | + | 10) | – | |
| 75 | + | 7 | = |
5) Fill in the missing numbers to find 84 + 7
| 84 | + | 7 | = | (84 | + | 10) | – | |
| 84 | + | 7 | = |
6) Fill in the missing numbers to find 75 + 8
| 75 | + | 8 | = | (75 | + | 10) | – | |
| 75 | + | 8 | = |
7) Fill in the missing numbers to find 93 + 9
| 93 | + | 9 | = | (93 | + | 10) | – | |
| 93 | + | 9 | = |
8) Fill in the missing numbers to find 54 + 7
| 54 | + | 7 | = | (54 | + | 10) | – | |
| 54 | + | 7 | = |
9) Fill in the missing numbers to find 45 + 7
| 45 | + | 7 | = | (45 | + | 10) | – | |
| 45 | + | 7 | = |
10) Fill in the missing numbers to find 78 + 7
| 78 | + | 7 | = | (78 | + | 10) | – | |
| 78 | + | 7 | = |
Answers:
1) 3 / 85
2) 1 / 45
3) 3 / 94
4) 3 / 82
5) 3 / 91
6) 2 / 83
7) 1 / 102
8) 3 / 61
9) 3 / 52
10) 3 / 85