When you are adding and subtracting decimals, there are two key things you need to do:
1) Line up your decimal points.
2) Fill in the decimals places, so there are the same amount in each question.
e.g. 4.75 + 2.4
Step 1: Set up the addition, taking care to line up your decimal points and add extra zeros where needed.
Step 2: Complete the addition as normal.
e.g. 3.845 - 0.48
Step 1: Set up the subtraction, taking care to line up your decimal points and add extra zeros.
Step 2: Complete the subtraction as normal.
Before you start this activity, grab a pen and paper so you can write out your own addition and subtraction sums to work them out.