This worksheet invites students to add hundredths and thousandths less than 1, which helps them become proficient in addition. In this worksheet, students add decimals by aligning the decimal points and using zero as a placeholder. They then use the relationship between addition and subtraction to find the missing number in the add hundredths and thousandths less than 1 worksheet. In each problem, the numbers are laid out in the horizontal format. Students should try to use different strategies involving composing and decomposing numbers to solve these problems. This will help them develop flexibility and fluency.