Tag: calculations and mental strategies 4

Place value chart of decimal number

$\displaystyle \frac { 142.0 }{ 14.2 } = \frac { 142.0 }{ 14.2 }\times \frac { 10 }{ 10 } = \frac { 1420 }{ 142 }=10 $

(68.12)*(2.5)=170.3

$\frac {280.5}{25.5}=\frac {280.5}{25.5}\times \frac {10}{10}\times \frac {10}{10}$
$=\frac {2805}{2.55}\times \frac {1}{100}=\frac {1100}{100}=11$

By BODMAS rule,
$2\times 0.5+9\div 0.3+10\times 0.92$
$=2\times 0.5+30+10\times 0.92$
$=1.0+30+9.2$
$=40.2$

$0.29\rightarrow 2$ decimal places
$0.27\rightarrow 2$ decimal places
$\therefore 0.29\times 0.27=0.0783$
$(2+2=4$ decimal places)

$1.000$
$+0.100$
$+0.010$
$\underline {+0.001}$
$\underline {1.111}$
$\Rightarrow 1.111\times 1000=1111$

Given expression $=\dfrac { { \left( 0.1 \right)  }^{ 3 }+{ \left( 0.02 \right)  }^{ 3 } }{ { 2 }^{ 3 }\left[ { \left( 0.1 \right)  }^{ 3 }+{ \left( 0.02 \right)  }^{ 3 } \right]  } =\dfrac { 1 }{ 8 } =0.125$

Given Expression $=\dfrac { { a }^{ 2 }-{ b }^{ 2 } }{ a-b } =\dfrac { \left( a+b \right) \left( a-b \right)  }{ \left( a-b \right)  } =\left( a+b \right) =\left( 2.39+1.61 \right) =4$

Given expression $=\dfrac { \left( 0.3333 \right)  }{ \left( 0.2222 \right)  } \times \dfrac { \left( 0.1667 \right) \left( 0.8333 \right)  }{ \left( 0.6667 \right) \left( 0.1250 \right)  } $