First, the addition formula

123+456 = 579 In this simple three-digit addition formula, we add two three digits. First, let's start with the unit and add 3 and 6 to get 9. Then, we add these ten digits, and then add 2 and 5 to get 7. Finally, we add hundreds of digits and add 1 and 4 to get 5. Therefore, 123+456 = 579.

234+567 = 80 1 In this slightly complicated three-digit addition formula, we also add from the unit. First, we add 3 and 7 to get 10, but since we can't write 0 into ten digits, we round it to a hundred digits. Next, we add 4 and 6 to get 10, and add the previous 1 to get 1 1. Therefore, 234+567 = 80 1.

Second, the subtraction formula

123-456 = -333 In this three-digit subtraction formula, we subtract one three-digit from another. First, let's subtract from the unit. Since 3 is less than 6, we need to borrow a seat. We subtract 5 from 2 in ten digits to get -3. Then we subtract 4 from 1 to get -3. Finally, we combine these three results and get -333.

234-567 = -333 In this similar three-digit subtraction formula, we also subtract from the unit. Because 4 is less than 7, we need to borrow a seat. We subtract 6 from 3 in ten digits to get -3. Then, we subtract 5 from 2 in hundreds to get -3. Finally, we combine these three results and get -333.

Application of addition and subtraction formula in life

I. Shopping budget

We often need to add and subtract when shopping. For example, if you have 100 yuan, and you want to buy a dress made in 50 yuan and a pair of shoes made in 30 yuan, you need to calculate whether your budget is enough.

In this case, the total price can be calculated by addition: 50+30 = 80 yuan. Then, you can check whether your money is enough by subtraction: 100-80 = 20 yuan. So, you have 20 yuan's budget balance.

Second, cooking ingredients

We also need to add and subtract when cooking. For example, if you want to make a fruit salad, you need 2 apples and 3 bananas. You need to calculate the number of fruits you need by addition: 2+3 = 5. Then, if you only have four apples, you need to use subtraction to determine what else you need: 5-4 = 1. So, you still need 1 apple.

Third, time management.

Addition and subtraction are also very useful in managing time. For example, if you have a task that takes 2 hours to complete and another task that takes 3 hours to complete, you can use addition to calculate the total time: 2+3 = 5 hours.

Then, if you only have 7 hours, you can use subtraction to determine whether you have enough time to complete all tasks: 7-5 = 2 hours. So, you still have two hours to finish other tasks.