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Теория: Умножение двузначных чисел

Задание

Перемножить числа:

   \(\displaystyle 7\)\(\displaystyle 6\)
  \(\displaystyle \times\)  
   \(\displaystyle 6\)\(\displaystyle 9\)
 
  
\(\displaystyle +\)    
  
 
 

 

Решение

1. Умножаем единицы числа \(\displaystyle 6\underline{9} \) (это число \(\displaystyle 9\)) на число \(\displaystyle 76{\small:}\)

 

\(\displaystyle 9 \cdot 76=684\) (здесь также можно использовать умножение в столбик).

 

   \(\displaystyle \bf7\)\(\displaystyle \bf6\)
  \(\displaystyle \times\)  
   \(\displaystyle 6\)\(\displaystyle \bf9\)
 
  \(\displaystyle \bf6\)\(\displaystyle \bf8\)\(\displaystyle \bf4\)
\(\displaystyle +\)    
 \(\displaystyle ?\)\(\displaystyle ?\)\(\displaystyle ?\) 
 
 \(\displaystyle ?\)\(\displaystyle ?\)\(\displaystyle ?\)\(\displaystyle ?\)

 

2. Умножаем десятки числа \(\displaystyle \underline{6}9\) (это цифра \(\displaystyle 6 \)) на число \(\displaystyle 76{\small:}\)

 

\(\displaystyle 6 \cdot 76=456 {\small.}\)

 

   \(\displaystyle \bf7\)\(\displaystyle \bf6\)
  \(\displaystyle \times\)  
   \(\displaystyle \bf6\)\(\displaystyle 9\)
 
  \(\displaystyle 6\)\(\displaystyle 8\)\(\displaystyle 4\)
\(\displaystyle +\)    
 \(\displaystyle \bf4\)\(\displaystyle \bf5\)\(\displaystyle \bf6\) 
 
 \(\displaystyle ?\)\(\displaystyle ?\)\(\displaystyle ?\)\(\displaystyle ?\)

 

Складываем числа:

  \(\displaystyle 6\)\(\displaystyle 8\)\(\displaystyle 4\)
\(\displaystyle +\)    
 \(\displaystyle 4\)\(\displaystyle 5\)\(\displaystyle 6\) 
 
 \(\displaystyle \bf5\)\(\displaystyle \bf2\)\(\displaystyle \bf4\)\(\displaystyle \bf4\)

 

В итоге мы получаем:

   \(\displaystyle 7\)\(\displaystyle 6\)
  \(\displaystyle \times\)  
   \(\displaystyle 6\)\(\displaystyle 9\)
 
  \(\displaystyle 6\)\(\displaystyle 8\)\(\displaystyle 4\)
\(\displaystyle +\)    
 \(\displaystyle 4\)\(\displaystyle 5\)\(\displaystyle 6\) 
 
 \(\displaystyle 5\)\(\displaystyle 2\)\(\displaystyle 4\)\(\displaystyle 4\)

Ответ: \(\displaystyle 5244{\small.} \)