Multiplying 5, 25, 125

Example 1

516 x 5 = ?

$$\begin{array}{l}516\times 5\\ =516\times \frac{10}{2}\\ =258\times 10=2580\end{array}$$
Example 2
317 x 5 = ?

$$\begin{array}{l}317\times 5\\ =316\times 5+5\\ =316\times \frac{10}{2}+5\\ =158\times 10+5=1585\end{array}$$
Example 3
6124 x 25 = ?

$$\begin{array}{l}6124\times 25\\ =6124\times \frac{100}{4}\\ =1531\times 100=153100\end{array}$$
Example 4
513 x 25 = ?

$$\begin{array}{l}513\times 25\\ =512\times 25+25\\ =512\times \frac{100}{4}+25\\ =128\times 100+25=12825\end{array}$$
Example 5
216 x 125 = ?

$$\begin{array}{l}216\times 125\\ =216\times \frac{1000}{8}\\ =27\times 1000=27000\end{array}$$
Example 6
631 x 125 = ?

$$\begin{array}{l}631\times 125\\ =624\times 125+7\times 125\\ =624\times \frac{1000}{8}+875\\ =78\times 1000+875\\ =78875\end{array}$$