1, add up to ten method: look at large numbers, divide them into decimals, add up to ten, and calculate.
For carry addition within 20, the decimal method is to divide the smaller number into several numbers and several numbers, use the larger number and one of them to make ten, and then add several to ten to get a result greater than ten.
2, break ten method: look at the decimal, divide by the large number, break ten, count.
Non-carry addition within (1)20: divide a dozen into ten digits and decimals, add an addend to the divided decimals, and then add the result to 10.
(2) Subtraction of abdication within 20: If the subtrahend is greater than the number in the subtrahend unit, write 10 on the side near the subtrahend subtract the result of that subtrahend with 10, and then add it to the number.
(3) Subtraction without abdication within 20 minutes: If the subtrahend is less than the single digit of the subtrahend, write the score near the subtrahend add 10 to the subtraction result.
The advantage of this is that students can master addition and subtraction within 20, and only need to master two methods, namely, adding ten and breaking ten. When breaking ten is applied to subtraction within 20, there is no need to abdicate.
Extended data
Mathematics [English: Mathematics, from ancient Greece μ? θξμα(máthēma)； Often abbreviated as math or maths], it is a discipline that studies concepts such as quantity, structure, change, space and information.
Mathematics is a universal means for human beings to strictly describe and deduce the abstract structure and mode of things, and can be applied to any problem in the real world. All mathematical objects are artificially defined in essence. In this sense, mathematics belongs to formal science, not natural science. Different mathematicians and philosophers have a series of views on the exact scope and definition of mathematics.
Mathematics plays an irreplaceable role in the development of human history and social life, and it is also an indispensable basic tool for studying and studying modern science and technology.