Subtracting decimals is very similar to adding them. By keeping your columns organized and following a few key rules, you can solve these problems with confidence!
When performing subtraction with decimals, remember these four points:
Convert to the Same Form: Ensure all given decimals are converted into the same form by adding placeholder zeros so they have the same number of decimal places.
Order Matters: The smaller number should always be written below the bigger number.
Align Place Values: Digits with the same place value must be written in the same vertical order. This ensures your decimal points are perfectly lined up.
Subtract Like Whole Numbers: Perform the subtraction just as you would with whole numbers.
Problem: Subtract $42.32$ from $83.95$.
Solution:
Step 1: Both numbers already have two decimal places, so they are in the same form.
Step 2: Place $83.95$ (the bigger number) on top and $42.32$ (the smaller number) below it, aligning the decimal points.
Step 3: Subtract column by column.
Final Answer: $83.95 – 42.32 = \mathbf{41.63}$.
Sometimes you will encounter problems that involve both addition and subtraction.
Problem: Find the value of $123.52 – 27.53 + 2353.254 – 167.2345$.
Solution Method:
Group and Add: First, add all the positive numbers together and all the negative numbers together separately.
$123.52 + 2353.254 = 2476.774$.
$27.53 + 167.2345 = 194.7645$.
Final Subtraction: Subtract the sum of the negative numbers from the sum of the positive numbers.
$2476.774 – 194.7645 = \mathbf{2262.0095}$.