$1$$kg=1000$$g$
\frac{1g}{1cm^3}=\frac{1000g}{xcm^3}
$x=1000$$cm^3=1$$dm^3$
…
1m^3=100*100*100=1000000cm^3
\frac{1g}{1cm^3}=\frac{xg}{1000000cm^3}
x=1000000g=1000kg=1t
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1m^3=1000l
1l=0,001m^3
27l=0,027m^3
V_{sz}=a^3
a=\sqrt[3]{V}=\sqrt[3]{0,027m^3}=0,3m=30cm
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250g=0,25l
0,25l=250cm^3
V=250cm^3
V{w}=\pi*r^2*H
r=6:2=3
250=3^2*H\pi
250\approx3,14*9*H
H\approx\frac{250}{28,26}\approx8,85cm