because there are 10 parts in the whole and 2 are shaded, the square can be represented as 2/10 shaded. this can be simplified to 1/5 since the numerator and denominator are both divisible by 2. to convert 1/5 to a decimal, we divide 1 by 5, which results in .2, which we can then convert to a percentage by moving the decimal place two times to the left. therefore, as a percent, the square is shaded 20%.
