Mathematics - Decimals - Adding and subtracting decimals - Line Up the Dots

5 steps: (1) To add/subtract decimals, first LINE UP THE DECIMAL POINTS. (2) Example: 3.45 + 2.7. Write vertically: 3.45 and 2.70 (add trailing zero to make same length). (3) Add column by column right to left, just like whole numbers. 5+0=5, 4+7=11 carry 1, 3+2+1=6. Answer: 6.15. (4) Subtraction: 5