let us do it by converting the 0.4 to a fraction, it has one decimal, so we'll use one zero at the denominator.
and 9.21 to a fraction as well, two decimals, thus two zeros at the denominator then,
[tex]\bf 9.21\div 0.4\\\\
-------------------------------\\\\
0.\underline{4}\implies \cfrac{04}{1\underline{0}}\implies \cfrac{4}{10}\implies \cfrac{2}{5}\qquad \qquad \qquad \qquad 9.\underline{21}\implies \cfrac{921}{1\underline{00}}\\\\
-------------------------------\\\\
9.21\div 0.4\implies \cfrac{921}{100}\div \cfrac{2}{5}\implies \cfrac{921}{100}\cdot \cfrac{5}{2}\implies \cfrac{921}{20}\cdot \cfrac{1}{2}\implies \cfrac{921}{40}
\\\\\\
23\frac{1}{40}\implies 23.025[/tex]
