When calculating, we should observe some units of numbers and see if any can make up a whole ten or a whole hundred. This is called the ten-complement method. When doing subtraction, it is not enough to subtract one place from one place, so we have to borrow one from ten places to subtract. This is called borrowing ten methods.
Borrowing ten is a calculation method used in the subtraction of abdication within 20. By borrowing ten, the abdication subtraction within 20 can be transformed into the familiar problem of 10 subtraction, which is difficult to simplify.
When calculating 13 minus 4, firstly, considering that single digit 3 minus 4 is not enough, we borrow 10 from ten digits to subtract, and 10 minus 4 gets 6, and then adding 6 to single digit 3 equals 9; This is the "borrowing ten methods".
For example:
15-9=( 10+5)-9=5+( 10-9)=5+ 1=6
On the line below 15, fill in 5 10 10-9= 1.
Extended data
The operation of decimal number is as follows: when adding: "every decimal one"; Subtraction: "Borrow one to be ten". In decimal numbers, different positions of numbers represent different values.
Decimal system is a number system based on 10. However, if all numerical values are represented by numbers not exceeding 10, then no matter how big the number is, it is represented by 1 0 times with one bit, 100 times with two bits, and so on, which is called decimal.
Binary system is also a "value system". The same number 1 represents different values with different digits. Such as 1 1 1, counting from right to left, the first 1 is one, the second1is two, the third1is four and the fourth/kloc-.