Problems from Multiplication and division of decimal numbers

Define two decimal numbers $$a$$ and $$b$$ of $$3$$ digits of integer part and $$3$$ digits of fractional part. Calculate its product and the $$a/b$$ division. Note: Use the following matrix to calculate the product:

            $$a_5$$ $$a_4$$ $$a_3$$ $$a_2$$ $$a_1$$ $$a_0$$
X           $$b_5$$ $$b_4$$ $$b_3$$ $$b_2$$ $$b_1$$ $$b_0$$
                       
                       
                       
                       
                       
                       
$$=$$ x x x x x x x x x x x

where $$a_0 \cdots a_5$$, $$b_0 \cdots b_5$$ are the digits of $$a$$ and $$b$$, respectively, and $$x$$ the digits of the result.

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Development:

$$a=783,623$$

$$b=126,961$$

$$a\cdot b:$$ The product is done without fractional digits and the comma is placed so that it has $$3+3=6$$ fractional digits.

            $$7$$ $$8$$ $$3,$$ $$6$$ $$2$$ $$3$$
X           $$1$$ $$2$$ $$6,$$ $$9$$ $$6$$ $$1$$
            $$7$$ $$8$$ $$3$$ $$6$$ $$2$$ $$3$$
        $$4$$ $$7$$ $$0$$ $$1$$ $$7$$ $$3$$ $$8$$  
      $$7$$ $$0$$ $$5$$ $$2$$ $$6$$ $$0$$ $$7$$    
    $$4$$ $$7$$ $$0$$ $$1$$ $$7$$ $$3$$ $$8$$      
  $$1$$ $$5$$ $$6$$ $$7$$ $$2$$ $$4$$ $$6$$        
  $$7$$ $$8$$ $$3$$ $$6$$ $$2$$ $$3$$          
$$=$$ $$9$$ $$9$$ $$4$$ $$8$$ $$9,$$ $$5$$ $$5$$ $$9$$ $$7$$ $$0$$ $$3$$

$$\dfrac{a}{b}$$: since the number of decimal is the same in $$a$$ and $$b$$, the commas can be ignored, and now compute the division of the integers $$\dfrac{(a\cdot1000)}{(b\cdot1000)}$$ $$\dfrac{a}{b}=6,17$$

Solution:

$$a\cdot b=99489,56$$

$$\dfrac{a}{b}=6,17$$

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