Final answer:
To change 0.421 to a percent, move the decimal point two places to the right and add the % symbol.
Step-by-step explanation:
To change a decimal to a percent, we move the decimal point two places to the right and add the % symbol. In this case, to change 0.421 to a percent, we move the decimal point two places to the right to get 42.1%.
Learn more about Converting decimals to percents