One or three digits:
This is a number with three numerical units. Such as: 212,256,468, etc. A natural number from 100 to 999.
Addition: Addition is one of the four basic operations, which refers to the operation of combining two or more numbers and quantities into one number and quantity. The symbol of addition is the plus sign "+". Connect items with a plus sign when adding.
Second, addition principle:
Addition has several important properties. They are interchangeable, that is, the order is not important, and they are interrelated, that is, when more than two numbers are added, the order of addition is not important. Repeated addition 1 is the same as counting, adding 0 does not change the result, and addition also follows related operations (such as subtraction and multiplication).
Addition is one of the simplest numerical tasks and the most basic addition: 1+ 1, five-month-old babies and even other animal species can be calculated. In primary education, students are taught to calculate the superposition of decimal numbers, starting with one digit, and gradually solving the difficult numerical calculation.
Calculation method:
Align the digits of two addends, and then add the numbers in the same counting unit separately. When the addition result exceeds 10, the high order will be removed, and the high order addition needs to accumulate the low order to 1.
Example: 182+472 problem solving process:
Step 1: 2+2=4.
Step 2: 8+7=5 to the high position, 1.
Step 3: 1+4+ 1=6.
According to the above calculation steps, the calculation result is 654.