What is 10 percent of 5kg?

0.5kg = 10% of 5kg

When changing percentages into decimal form you just take 1 and divide it by the percentage (e.g. 1/10 = 0.1). then you just multiply the decimal by the number you are trying to extract the percentage from (e.g. 0.1 x 5 [kg] = 0.5 [kg]). Viola you have your percentage.