0,1) 5 ​ ⋅10 −1 .

It seems like you have written down a number in scientific notation. The expression \( 5 \cdot 10^{-1} \) represents the number 0.5 in decimal form.

Here’s a breakdown:

• \( 10^{-1} \) means \( \frac{1}{10} \), which is 0.1.
• Multiplying by 5 gives \( 5 \cdot 0.1 = 0.5 \).

Thus, \( 5 \cdot 10^{-1} \) equals 0.5. If you need any further assistance or clarification, feel free to ask!