How do you solve 612-405?

Jul 16, 2016

$207$

Explanation:

$612 - 405 = 207$

Use calculator or write out math

Jul 17, 2016

207

Explanation:

There are several ways this type of question can be approached. I am going to show you two methods.

$\textcolor{b l u e}{\text{Method 1 - Splitting the numbers (partitioning)}}$
Write $612 \text{ as } 600 + 12$
Write $405 \text{ as } 400 + 5$

Now write them as:

$\text{ } 600 + 12$
$\text{ "ul(400+5)larr" Subtract}$
$\text{ } 200 + 7$

Answer $207$
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$\textcolor{b l u e}{\text{Method 2 - This is the more traditional way}}$

$\textcolor{b r o w n}{\text{It is the same thing as method 1 but in disguise}}$

Write as:

$\text{ } 61 \textcolor{m a \ge n t a}{2}$
$\text{ } \underline{40 \textcolor{m a \ge n t a}{5}}$

$\textcolor{m a \ge n t a}{\text{Consider the right hand column (units)}}$

The 2 is less than 5 so move one of the tens to the units. Then the 1 in 12 becomes 0 and the 2 in 12 becomes $10 + 2 = 12$ giving

$\text{ } 6 {\cancel{1}}^{0} {\cancel{2}}^{12}$
$\text{ "ul(4color(white)(.)0color(white)(.)5) larr" Subtract}$
$\text{ } 2 \textcolor{w h i t e}{.} 0 \textcolor{w h i t e}{.} 7$