Question

Using the shorter method, simplify the given one.

$31978-9999$

Answer 1

As we know,$9999$ can be written as $(10000-1)$ so,

$$\begin{gathered} =31978-(10000-1) \\ =31978-10000+1 \\ =21978+1 \\ =\mathbf{21979} \end{gathered}$$

Thus, the required answer is $\mathbf{21979}$.