Multiply a fivedigit number by a singledigit number
1.1. Knowledge to remember
14273 x 3 = ?
\(\begin{array}{l}
\underline { \times \begin{array}{*{20}{c}}
{14273}\\
{\,\,\,\,\,\,\,\,\,\,\,3}
\end{array}} \\
\,\,\,\,\,42819
\end{array}\)
14273 x 3 = …
 3 times 3 equals 9, write 9.
 3 times 7 equals 21, write 1 remember 2.
 3 times 2 equals 6 , add 2 equals 8, write 8.
 3 times 4 equals 12, write 2 remember 1.
 3 times 1 equals 3, add 1 equals 4, write 4.
1.2. Solving Textbook Exercises
Lesson 1: Calculate
\(\underline { \times \begin{array}{*{20}{c}}
{21526}\\
{\,\,\,\,\,\,\,\,\,\,\,3}
\end{array}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underline { \times \begin{array} {*{20}{c}}
{40729}\\
{\,\,\,\,\,\,\,\,\,\,\,2}
\end{array}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underline { \ times \begin{array}{*{20}{c}}
{17092}\\
{\,\,\,\,\,\,\,\,\,\,\,4}
\end{array}} \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\underline { \times \begin{array}{*{20}{c}}
{15180}\\
{\,\,\,\,\,\,\,\,\,\,\,5}
\end{array}} \)
Solution guide:
 Perform multiplication from right to left.
\(\begin{array}{l}
\underline { \times \begin{array}{*{20}{c}}
{21526}\\
{\,\,\,\,\,\,\,\,\,\,\,3}
\end{array}} \\
\,\,\,\,\,64578
\end{array}\) \(\begin{array}{l}
\underline { \times \begin{array}{*{20}{c}}
{40729}\\
{\,\,\,\,\,\,\,\,\,\,\,2}
\end{array}} \\
\,\,\,\,\,81458
\end{array}\) \(\begin{array}{l}
\underline { \times \begin{array}{*{20}{c}}
{17092}\\
{\,\,\,\,\,\,\,\,\,\,\,4}
\end{array}} \\
\,\,\,\,\,68368
\end{array}\) \(\begin{array}{l}
\underline { \times \begin{array}{*{20}{c}}
{15180}\\
{\,\,\,\,\,\,\,\,\,\,\,5}
\end{array}} \\
\,\,\,\,\,75900
\end{array}\)
Lesson 2: Number ?
Factor 
19091 
13070 
10709 
Factor 
5 
6 
7 
Tick 


Solution guide:
 Find the value of the multiplication of two given factors and then fill in the result in the value of product box.
Factor 
19091 
13070 
10709 
Factor 
5 
6 
7 
Tick 
95455 
78420 
74963 
Lesson 3: The first time people moved 27 150 kg of paddy into the warehouse, the next time the amount of paddy was doubled the first time. How many kilograms of rice were transferred to the warehouse both times?
Solution guide:
Summary:
 Find the mass of paddy transferred in the second time.
 Find the mass of both transfers.
Solution
Method 1:
Number of kilograms of paddy to be transferred next time:
27150 x 2 = 54300 (kg)
Both transfers to the warehouse are:
27150 + 54300 = 81450 (kg)
Answer: 81450 kg.
Method 2:
Considering 27159 kg of paddy transferred for the first time as 1 part, the next time it is transferred 2 parts. The total number of equal parts is :
1 + 2 = 3 (parts)
Both transfers are:
27150 x 3 = 81450 (kg)
Answer: 81450 kg.
.
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