Look at large numbers, divide them into decimals, make up ten, and add up the remainder. Remember large numbers in your mind and decimals in your hand. One plus nine, ten tadpoles, two plus eight, ten old ducks, three plus seven, ten old hens, four plus six, ten golden monkeys, five plus five, and ten big tigers. Think of 1 when you see 9, 2 when you see 8, 3 when you see 7, and 4 when you see 6. When you see the big corner decimal system, switch the two numbers first.
As one of the basic operations of mathematics, addition and subtraction plays an important role in daily life and study. Whether it is simple digital addition or complex formula operation, it is essential to master the calculation methods and skills of addition and subtraction. This paper will explain the calculation method of addition and subtraction in detail, and introduce some practical skills, and at the same time quote related books to explain.
The Art of Computing
1, carry and borrow: In addition and subtraction, carry and borrow are common situations. Carry means that when the sum or difference of a bit is greater than or equal to 10, it goes to the high position of 1. Borrowing means borrowing 1 from the high position if the minuend is less than the minuend in subtraction. These two skills should be paid attention to in the calculation process.
2. Estimation: When dealing with large numbers, you can estimate the sum or difference of each bit first, and then make an accurate calculation. This can reduce the chance of misjudgment.
3. Column Vertical: For complex addition and subtraction operations, the calculation process can be listed vertically, which is clearer and easier to operate.
4. Digit grouping: when adding or subtracting multiple digits, it can be grouped by digits, which is convenient for bit-by-bit calculation.