Don't forget to put decimal point in the product!
Fill in the blanks.
26.4×4=( )+( )+( )+( )
2. The magnification of 3.67 10 is (), the magnification of 100 is () and the magnification of 1000 is ().
3.560 minus 10 is (), minus 100 is (), minus 1000 is ().
Second, the calculation
1, the number is written directly.
6.5× 10= 0.56× 100= 3.78× 100=
3.2 15× 100= 0.8× 10= 4.08× 100=
2, with vertical calculation
4.6×6= 8.9×7= 15.6× 13=
0. 18× 15= 0.025× 14= 3.06×36=
Third, according to 13×3=39, quickly say the product of the following questions.
130×3= 13×30= 1.3×3=
1300×3= 130×30= 0. 13×3=
1, do not count, fill in the box >; ,< or =
198×0.8 198 95×0.9 95
168× 1.5 168 132×4.6 132
2. First calculate the first three questions, then carefully observe and find out the rules, then complete other formulas and write numbers directly.
1.23×9=
1.234×9=
1.2345×9=
( )×9=
( )×9=
3.6 3
× 1 ( )
7 ( )( )
3 6 3
( ) 3 5 6
Section 2 Decimal Multiplying Decimal System
Be careful when calculating decimal places!
fill (up) a vacancy
The product of 1 and 6.3× 16.789 has () decimal places.
2. Write the product of the following questions directly according to 47× 14=658.
0.47× 14= 4.7× 14= 0.47× 1.4=
47×0. 14= 0.47×0. 14= 470×0.0 14=
Please fill in >,< or = in the box.
196×0.8 196 35×2.5 35
0.78× 1. 1 0.78 6.2×0.99 6.2
If a × 0.56 >; 0.56, and then a 1.
If b × 0.42
Second, the question of right or wrong (tick right, X wrong)
When the multiplier ratio is 1 hour, the product must be less than the multiplicand. ( )
1.5 times of a number must be greater than the original number. ( )
Two decimal places are multiplied by one decimal place, and the product has at most three decimal places. ( )
4.37×3.8= 166.06( )
When calculating decimal multiplication vertically, the decimal points in the factor should be aligned. ( )
Third, calculate the following questions
3 1.5×24.5 0.8×0.56 4.23×0.028
0.63× 1.05 36×0.56 0.32×0.2
When a is what value, the following equation holds:
2.6× 1.5+a× 1.5+0. 15×34 = 76×0. 15
Part III Approximate Quantity of Products
Remember the "four hospitals" and "five doors"!
I. Fill in the blanks:
1, 6.9628 reserved integer is (); Retained to the tenth place is (); Keep two decimal places is (); Keep three decimal places is ()
2. Find the approximate value of decimal. If you keep three decimal places, it depends on the position of the decimal point ().
The product of 3.4.3×0.83 is (), and it is about () after retaining two decimal places.
4. Two decimal places are rounded to one decimal place to get 3.0. The maximum possible quantity is (), and the minimum possible quantity is ().
Second, the judgment question. (Tick √ for the right and × for the wrong)
1, approximate values of 4.0 and 4 are equal in size and accuracy. ( )
2, 7.995, accurate to one percent, is 8. ( )
When a natural number is multiplied by a decimal, the product must be less than this natural number. ( )
4. The approximate value of the product of two numbers with two decimal places is 2. 16, and this exact number may be 2. 156 ().
Third, calculation
1, with one decimal place reserved.
3.58×2 0.5×0.9 0.37×2.4
2. Keep the number to two decimal places.
35.6×0.506 6.728×3.2 34.3×0.23
The fourth quarter multiplication, multiplication and addition, multiplication and subtraction
Don't worry, it's an order of magnitude with an integer!
I. Fill in the blanks:
3 minus the product of 0.25 and 4, the difference is ().
0.5 times 16 minus the product of 7. 15, and the difference is ().
2.4 subtract 0.8 and add 0.4 to get ()
The product of 3.8 times 1.2, and the expansion of 100 times is ()
Second, the calculation of the following problems is out of step.
8.9× 1. 1×4.7 2.7×5.4×3.9
3.6×9.85-5.46 8.05×3.4+7.6
6.58×4.5×0.9 2.8×0.5+ 1.58
Third, the following questions are calculated continuously.
What is the product of 3.4 and 2.45 times 1.2?
What is five times the product of 1.35 times 2.6?
How much is 3.05 less than 0.5 times of 65438+4.7?
Calculation:
0. 1+0.3+0.5+0.7+0.9+0. 1 1+0. 13+0. 15+0. 17+0. 19+……+0.99
Section 5 The Generalization of Multiplication Law in Decimal Multiplication
Little doctor tip:
How interesting! Multiplication commutative law, associative law and distributive law are also useful in fractional multiplication!
1, according to the algorithm, fill in the appropriate numbers on the horizontal line below, and fill in the operation symbols in the box.
59×2.5×0.4= ×( × )
7.8× 15+2.2× 15=( + )× 15
0.02× 1.25×5×8=( × )×( × )
9.63×2.5+9.63×7.5= ( )
×0.2+3× =( +40)×3
×0.8+5× =( +39.2)×5
0.63×99+0.63=( )
2. Connect the left and right equations with lines.
(5+8)×0.4 9×5+9× 1.6
4.6× 19+5.4× 19 5×0.4+8×0.4
9×(5+ 1.6) (4.6+5.4) × 19
3.6×4×2.5 3.6×(4×2.5)
3. Calculate the following questions in a simple way.
2.5×(3.8×0.04) 7.69× 10 1
(8×5.27) × 1.25 46×0.33+54×0.33
0.25×39+0.25 0. 125×72
1, the following questions, how to calculate how simple.
9.8+99×9.8 1.25×88
4.65×32+2.5×46.5+0.465×430
7.25×67.875+725×0.7875+7250×0.053375
Compare the sizes of the following two products.
a = 139.54×2.3 17 B = 139.55×2.3 16
A b
Unit 1 examination questions
Intelligent network:
1, 13.65 magnification () times is1365; 6.8 Reduction () times is 0.068.
2. Write down 7. 47860.678786786 ... Use a simple method as () and keep two decimal places as ().
3. Keep 7. 1687 as an integer around (), and the accuracy is around ().
The product of 4.4.09×0.05 has () decimal places, and the product of 5.2×4.76 has () decimal places.
5. According to 13×28=364, quickly write the following products.
1.3×2.8= 0. 13×0.28= 13×2.8=
0.0 13×28= 0. 13×2.8= 1.3×0.028=
6. Please fill in >,< or = in the box.
163×0.8 163 36×2.8 36
7. True or false (tick correctly and cross wrongly)
① The product of 0.03 and 0.04 is 0. 12. ( )
② 65438+ 0.65 times of a number must be greater than this number. ( )
③ 53.78 Keep one decimal place as 53.8. ( )
4. A number multiplied by a decimal must be less than this number. ( )
8. Choose (put the serial number of the correct answer in brackets)
(1), the decimal point of a decimal point has been moved 2 places to the right and 3 places to the left, and this decimal point ().
A, expand 10 times b, shrink 10 times c, expand 100 times d, shrink 1000 times.
5. The following category with a score less than 0.85 is ().
a、0.85× 1.0 1 B、0.85×0.99 C、0.85× 1
9. Write the number directly.
0.6×0.8 3×0.9 2.5×0.4 3.6×0.4
12.5×8 50×0.04 80×0.3 1. 1×9
10, column calculation.
3.08×0.43 13.5×26.7 48×0.35
1 1, off-type calculation (simple calculation if it can be simplified)
12.5×0.4×2.5×8 9.5× 10 1
4.2×7.8+2.2×4.2 0.87×3. 16+4.64
Online application:
1, 1.25 times 4.2 minus 5, what's the difference?
How much is 2.3.05, which is more than 0.5 times of 65438+4.7?