Decimal multiplication is a difficult and necessary test point in the first volume of grade five. About three weeks after the start of school, the first unit of the People's Education Edition should have come to an end and began to prepare for the unit test. So what knowledge points and test sites need to be memorized and mastered in this unit of decimal multiplication? Teacher Tian Tian summarized as follows:

1, the significance and calculation method of fractional multiplication;

The meaning of decimal multiplication by integer: a simple operation to find the sum of several identical addends (the same meaning as integer multiplication). For example, 1.5×3 indicates what is three times of 1.5, or what is the sum of three 1.5.

The meaning of multiplying decimal by decimal is to find out how many tenths (hundreds/thousands) of this number, or how many times a number is.

For example, 1.5×0.8 (the integer part is 0) is to find eight tenths of 1.5.

1.5× 1.8 (integer part is not 0) is 1.8 times of 1.5.

Decimal multiplication calculation method: first move the decimal point of the factor to the right, and expand the decimal point into an integer (or directly calculate the decimal point into an integer without looking at the decimal point); Then the product is calculated according to the calculation rules of integer multiplication; Look at how many decimal places a factor * * * has. Just count the decimal places from the right side of the product. Note: In the calculation results, the 0 at the end of the decimal part should be removed to simplify the decimal; When the number of decimal places is not enough, it needs to be filled in the position of 0.