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Theory: Subtraction from two-digit numbers

Task

Subtract the numbers:

\(\displaystyle -\) \(\displaystyle 6\) \(\displaystyle 7\)
\(\displaystyle 5\) \(\displaystyle 7\)
 

 

Solution

For subtracting whole numbers one can write the subtrahend under the minuend in columns, so that the place values are lined up.

 

1. Subtract from the ones of \(\displaystyle 6\color{red}{7}\) (it is number \(\displaystyle \color{red}{7}\)) the ones of \(\displaystyle 5\color{red}{7}\) (it is number \(\displaystyle \color{red}{7}\)):

\(\displaystyle \color{red}{7}-\color{red}{7}=\color{red}{0}{\small . }\)

\(\displaystyle -\) \(\displaystyle 6\) \(\displaystyle \color{red}{ 7}\)
\(\displaystyle 5\) \(\displaystyle \color{red}{ 7}\)
  \(\displaystyle ?\) \(\displaystyle \color{red}{ 0}\)

 

2. Subtract from the tens of \(\displaystyle \color{red}{6}7\) (it is number \(\displaystyle \color{red}{6}\)) the tens of \(\displaystyle \color{red}{5}7\) (it is number \(\displaystyle \color{red}{5}\)):

\(\displaystyle \color{red}{6}-\color{red}{5}=\color{red}{1}{\small . }\)

\(\displaystyle -\) \(\displaystyle \color{red}{ 6}\) \(\displaystyle 7\)
\(\displaystyle \color{red}{ 5}\) \(\displaystyle 7\)
  \(\displaystyle \color{red}{ 1}\) \(\displaystyle 0\)

So,

 

\(\displaystyle -\) \(\displaystyle 6\) \(\displaystyle 7\)
\(\displaystyle 5\) \(\displaystyle 7\)
  \(\displaystyle 1\) \(\displaystyle 0\)

 

Answer: \(\displaystyle 10{\small .}\)