Learn how to use mental and written strategies for adding and subtracting two, three, four, and five-digit numbers with step-by-step examples and techniques for easy understanding.
When we talk about using mental and written strategies for adding and subtracting numbers, it simply means that we have different ways to do math in our heads or on paper. Let's start with addition. Imagine you have to add two numbers together, like 25 + 16. One way to do this is by carrying over the numbers in your head. You can break down the numbers into tens and ones, so adding 20 + 10 in your head first, which equals 30, and then adding 5 + 6, which equals 11. Finally, you combine these two results to get the final answer, 30 + 11 = 41. This is an example of a mental strategy for addition.
Now, let's look at a written strategy for addition. If you have to add larger numbers like 345 + 278, you can line up the numbers vertically and add each column starting from the right side. You add the ones column first (5 + 8), which equals 13, then write down 3 and carry over 1 to the tens column. Next, add the tens column (4 + 7 + 1), which equals 12. This way, you continue adding each column until you reach the leftmost column to get the final answer, 623.
For subtraction involving multiple-digit numbers, you can also use mental and written strategies. In mental subtraction, you can break down the numbers and subtract them in parts. For example, if you need to subtract 544 - 237, you can first subtract the hundreds (500 -200), then the tens (40 -30), and finally the ones (4 - 7). This helps you break down the problem into smaller steps for an easier solution.
In written subtraction, you can line up the numbers vertically, just like in addition, and borrow when necessary to subtract each column. For instance, when subtracting 657 - 289, if the top number is smaller than the bottom number in a column, you borrow from the column to the left. By following this method, you can subtract each column and get the correct answer, 368.
By practicing these mental and written strategies with different digit numbers, you can become more confident and skilled in adding and subtracting larger numbers efficiently.