Question

What is

`8.4 - 4.2`
8.4 - 4.2 ​

Answer 1

4.2

Explanation:

`\mathrm{Write\:the\:numbers\:one\:under\:the\:other,\:line\:up\:the\:decimal\:points.}`

`\mathrm{Add\:trailing\:zeroes\:so\:the\:numbers\:have\:the\:same\:length.}`

`\begin{matrix}\space\space&8&.&4\\ -&4&.&2\end{matrix}`

`\mathrm{Subtract\:each\:column\:of\:digits,\:starting\:from\:the\:right\:and\:working\:left}`

`\mathrm{In\:the\:bolded\:column,\:subtract\:the\:second\:digit\:from\:the\:first}:\quad \:4-2=2`

`\frac{\begin{matrix}\space\space&8&.&\textbf{4}\\ -&4&.&\textbf{2}\end{matrix}}{\begin{matrix}\space\space&\space\space&\space\space&\textbf{2}\end{matrix}}`

`\mathrm{Place\:the\:decimal\:point\:in\:the\:answer\:directly\:below\:the\:decimal\:points\:in\:the\:terms}`

`\frac{\begin{matrix}\space\space&8&\textbf{.}&4\\ -&4&\textbf{.}&2\end{matrix}}{\begin{matrix}\space\space&\space\space&\textbf{.}&2\end{matrix}}`

`\mathrm{In\:the\:bolded\:column,\:subtract\:the\:second\:digit\:from\:the\:first}:\quad \:8-4=4`

`\frac{\begin{matrix}\space\space&\textbf{8}&.&4\\ -&\textbf{4}&.&2\end{matrix}}{\begin{matrix}\space\space&\textbf{4}&.&2\end{matrix}}`

`=4.2`