Addition and subtraction of two decimal places, what are the addition and subtraction of two decimal

It's finally good. There are probably more than 30 questions, but I didn't count them carefully.

Two-digit addition and subtraction quick calculation method:

Carry addition formulas for two-digit plus two-digit numbers: add 9 to subtract 1, add 8 to subtract 2, add 7 to subtract 3, add 6 to subtract 4, add 5 to subtract 5, add 4 to subtract 6, add 3 to subtract 7, add 2 to subtract 8, add 1 to subtract 9.

Abdication subtraction of two digits minus two digits.

Formula: minus 9 to add 1, minus 8 to add 2, minus 7 to add 3, minus 6 to add 4, minus 5 to add 5, minus 4 to add 6, minus 3 to add 7, minus 2 to add 8, minus 1 to add 9.

Addition Banquet Rules:

When using the "truncation method" in addition or subtraction, add or subtract directly from the left high position (while paying attention to whether the next digit needs to be carried or misplaced) until you get the answer that the option requires precision. When using the "truncation method" in multiplication or division, in order to make the result as accurate as possible, it is necessary to pay attention to the direction of the approximation of the truncation:

1. To expand (or shrink) one multiplier factor, it is necessary to shrink (or expand) another multiplier factor.

2. Expand (or shrink) the dividend.

You need to expand (or shrink) the divisor. If you are looking for the sum or difference of the products of two times (i.e., a*b+ -c*d).

3. If one side of the plus sign is enlarged (or reduced), the other side of the plus sign needs to be narrowed (or expanded).

4. Enlarge (or reduce) one side of the minus sign, then enlarge (or reduce) the other side of the minus sign.

3) 10. 7) The first chant trembles.

Some of the above topics can be calculated in a simple way by using the commutative law of the adder, here I will not explain them one by one, the addition and subtraction of decimals and decimals, for beginners or column vertical calculation, decimal addition calculation is integer plus integer, decimal plus decimal, decimal part is enough 1 to go up one place.

Two-digit addition and subtraction refers to the process and result of adding and subtracting at least one of the two integers, at least one of which is a two-digit number. Two-digit addition and subtraction is one of the most important fundamentals in primary school mathematics, and children usually learn it in the second or third grade of primary school.

For two-digit addition and subtraction, we can use the method of vertical calculation. In the vertical pose, we line the added, subtracted, plus, minus, and resulted Wang Yuna on a vertical line. Addition and subtraction are performed on the corresponding bits, and special handling is required in the case of carrying.

For example, for 23+34, we first add in the single digit to get 7, then add in the ten digits and consider the carry to get 5, and finally get 57. For 87-24, we first subtract the single digit to get 3, then subtract the ten digits and consider the borrowed digit to get 6, and finally get 63.

In general, we need to master the methods of carry and borrow, understand the basic rules of addition and subtraction, and how to solve abnormal situations. When doing addition and subtraction calculations, we should first understand the problem clearly, and then carefully check the calculation process and results to avoid mistakes.

It is worth reminding that many children or those who are not familiar with mathematical calculations may prefer to use technical devices such as calculators or grinding computers to perform calculations in contrast to hand calculations. This is undoubtedly a convenient and quick method, but it can also affect children's ability and confidence building in mathematics. Therefore, allowing children to do hand arithmetic and mathematical thinking can help them better understand and master mathematics.

In short, for two-digit addition and subtraction, children need to gradually master the rules and skills through classroom learning and practice. At the same time, hand arithmetic can help children improve their numeracy and mathematical thinking skills, build confidence, and help them achieve better results in further mathematics learning in the future. <>

Addition. Positive numbers are added to positive numbers, and the sum is positive; For example, 3+5=8

Negative numbers are added to negative numbers, and the sum is negative; For example, (-3) + (5) = -8 positive and negative numbers are added, and the absolute value is larger to make a noisy friend symbol, and the absolute value is subtracted;

Such as (pure crack +3) + (5) = -2 ; (3) + (5) = +2 subtraction. Subtracting another number from one number is equal to the opposite number of one number plus another, and then calculated according to the above 3 items.

For example, (+3)-(5)=(3)+(5) then calculate according to the method;

3)-(5)=(3)+(5) and then calculate according to the method;

3)-(5)=(3)+(5) and then calculate according to the method;