Exercises: Subtraction

$45-12-10$

Subtract from right to left. Subtract the ones first: $5-2=3$

$\begin{array}{l}45\\ -12\\ \underline{-10}\\ 3\end{array}$

Now subtract the tens: $4-1-1=2$.

$\begin{array}{l}45\\ -12\\ \underline{-10}\\ 23\end{array}$

The result is therefore 23.

$58-13-4$

Subtract from right to left. Subtract the ones first: $8-3-4=1$.

$\begin{array}{l}58\\ -13\\ \underline{-4}\\ 1\end{array}$

Now subtract the tens: $5-1=4$.

$\begin{array}{l}58\\ -13\\ \underline{-4}\\ 41\end{array}$

The result is therefore 41.

$87-65-12$

$\begin{array}{l}87\\ -65\\ \underline{-12}\\ 0\end{array}$

Now subtract the tens: $8-6-1=1$.

$\begin{array}{l}87\\ -65\\ \underline{-12}\\ 10\end{array}$

The result is therefore 10.

$90-15-58$

Subtract from right to left. Subtract the ones first. Since $5+8$ is greater than $0$, and even greater than $10$ you need to calculate $20-5-8=7$ instead and memorize a $2$ at the tens digit.

$\begin{array}{l}90\\ -15\\ \underline{-5_{2}8}\\ 7\end{array}$

Now subtract the tens: $9-1-5-2=1$.

$\begin{array}{l}90\\ -15\\ \underline{-5_{2}8}\\ 17\end{array}$

The result is therefore 17.

$87-25-50$

Subtract from right to left. Subtract the ones first: $7-5=2$.

$\begin{array}{l}87\\ -25\\ \underline{-50}\\ 2\end{array}$

Now subtract the tens: $8-2-5=1$.

$\begin{array}{l}87\\ -25\\ \underline{-50}\\ 12\end{array}$

The result is therefore 12.

$96-37-25$

Subtract from right to left. Subtract the ones first. Since $(7+5)$ is greater than $6$, you need to calculate $16-(7+5)=4$ instead and memorize a $1$ at the tens digit.

$\begin{array}{l}96\\ -37\\ \underline{-2_{1}5}\\ 4\end{array}$

Now subtract the tens: $9-3-2-1=3$

$\begin{array}{l}96\\ -37\\ \underline{-2_{1}5}\\ 34\end{array}$

The result is therefore 34.