When we're dealing with more than one number in an equation, the numbers might not have the same number of digits. For instance, an equation might have one number that has two digits and one number with only one digit. Still, we don't always have to use column addition. We can save ourselves some time by solving the problem mentally.
If you can add two digits, you can find the answer to the problem.
Look at this addition problem:
26 + 2 =
Let's underline the digits in the ones place.
26 + 2 =
The underlined digits show 6 + 2. What's the answer? It's 8. Use this number to solve the problem. If 6 + 2 equals 8, then what is 26 + 2? The answer is 28.
Let's try some more.
54 + 5 =
The underlined digits show 4 + 5. What's the answer? The answer is 9. So what is 54 + 5? Right: 54 + 5 equals 59.
The underlined digits help you figure out the answer.
83 + 2 =
The underlined digits show 3 + 2. What's the answer? It's 5. So what is 83 + 2? It's 85.
