Задание 158

Решение:

• $${\largeа)}\ 2{,}35\cdot3{,}251\approx2{,}4\cdot3{,}3\approx7{,}92\approx7{,}9$$

• $$\begin{array}{r}\times\begin{array}{r}2{,}4\\3{,}3\\\hline\end{array}\phantom{0}\\\begin{array}{r}+\begin{array}{r}72\\72\phantom{0}\\\hline\end{array}\\\begin{array}{r}7{,}92\end{array}\end{array}\end{array}$$

• $${\largeб)}\ {-}4{,}3205\cdot2{,}503\approx{-}4{,}3\cdot2{,}5\approx{-}10{,}75\approx{-}11$$

• $$\begin{array}{r}\times\begin{array}{r}4{,}3\\2{,}5\\\hline\end{array}\phantom{0}\\\begin{array}{r}+\begin{array}{r}215\\86\phantom{0}\\\hline\end{array}\\\begin{array}{r}10{,}75\end{array}\end{array}\end{array}$$

• $${\largeв)}\ 3\cdot2{,}(1)=3\cdot2{,}111{...}\approx3\cdot2{,}1\approx6{,}3$$

• $$\begin{array}{r}\times\begin{array}{r}2{,}1\\3\\\hline\end{array}\\\begin{array}{r}6{,}3\end{array}\end{array}$$

• $${\largeг)}\ 0{,}56\cdot0{,}(3)=0{,}56\cdot0{,}333{...}\approx0{,}56\cdot0{,}33\approx0{,}1848\approx0{,}18$$

• $$\begin{array}{r}\times\begin{array}{r}0{,}56\\0{,}33\\\hline\end{array}\phantom{0}\\\begin{array}{r}+\begin{array}{r}168\\168\phantom{0}\\\hline\end{array}\\\begin{array}{r}0{,}1848\end{array}\end{array}\end{array}$$

• $${\largeд)}\ 0{,}(1)\cdot0{,}(2)=0{,}111{...}\cdot0{,}222{...}\approx0{,}11\cdot0{,}22\approx0{,}0242\approx0{,}024$$

• $$\begin{array}{r}\times\begin{array}{r}0{,}11\\0{,}22\\\hline\end{array}\phantom{0}\\\begin{array}{r}+\begin{array}{r}22\\22\phantom{0}\\\hline\end{array}\\\begin{array}{r}0{,}0242\end{array}\end{array}\end{array}$$

• $${\largeе)}\ 12{,}(45)\cdot10{,}(1)=12{,}4545{...}\cdot10{,}1111{...}\approx12\cdot10\approx120$$

• $$\begin{array}{r}\times\begin{array}{r}12\phantom{0}\\10\\\hline\end{array}\\\begin{array}{r}120\end{array}\end{array}$$