This worksheet gives students an opportunity to apply the concepts of addition to add hundredths and thousandths less than 1 with regrouping. Students use the relationship between addition and subtraction to find the missing number while adding decimals. To reach the answer, they must also regroup the numbers in add hundredths and thousandths less than 1 with regrouping worksheet using the relationships between ones, tenths, hundredths, thousandths, etc.