Four and one-two-five, and one-two-five, and many of the students write it as one-two-five times four, and then one-eight times one-two-five, so that one-two-five times four equals one, eight-point-five equals one-two。
Why don't you do that? Can you do that? Is it not a whole? As a whole, a multiplication ratio can be used to treat 0. 25 and 1. 225 as a whole, multiplying four and eight, respectively, so it is not right to open them separately。
Of course, in doing this, it is important to understand the meaning of the decimal multiplication, to continue to calculate the decimal multiplication, to calculate the accumulation in accordance with the integer multiplication method, and to look at the number of decimals in the factor, to count from the bottom of the accumulation, to point one, to look at it later。
What should we do about this? One of the students said it could be considered as 4. 08, so that it could be multiplied using multiplication rates。
First, we switch positions for 1:25 and 4 plus 0. 8, and then the first one turns to 0. 25 by 1:25 by 1:25 by 4
What can be done at this point? The exchange and integration rates using multiplications, such as 0. 25 and 41, will be replaced by four and 1:25, which will remain unchanged. The same goes for 1:25 and 00:08, right? Zero twenty-five, one parenthesis, one twenty-five times zero eight。
Now look at the meaning of the decimal here. Twenty-five times four equals what? That's one hundred. How many decimals did you have in the factor? Two? Twenty-five? Two? So the last number at g is seven. It's zero. Count one more, right? So, 1 0, 1 0, 1 0 is one? One times two and a half is one and a twenty-five plus one and a twenty-five and an eight, and 125 times eight equals what? That's one thousand。
How many decimals are in this? Two plus three in the back, so it's 1 010, 1 010 times 0 05, isn't it? So add 05. What's the end result? One hundred and twenty-five plus one twenty-five is one and a half, which is the simple method of budgeting this issue. If written at 4. 8, there is no such method。
That's the point, thank you。
