Adding and Subtracting Decimals

Adding and Subtracting Decimals Concept Explanation:

Adding and subtracting decimals is similar to whole numbers, but you need to align the decimal points. This ensures you are adding/subtracting digits that have the same place value.

Steps to add or subtract decimals:

Write the numbers so that their decimal points are aligned.
If necessary, add zeros to the end of one of the numbers to make sure both numbers have the same number of decimal places.
Add or subtract as you would with whole numbers.
Place the decimal point in the answer directly under the decimal points in the numbers being added or subtracted.

Diagram:

Here’s an example of adding decimals $4.37 + 2.641$ :

$\begin{array}{c} \begin{aligned} &\phantom{0}4.370 \ <ul> <li>&\phantom{0}2.641 \ &\underline{<del>~</del>~~} \ &\phantom{0}7.011 \end{aligned} \end{array}$

Hard Questions:

Q1: Add $12.43 + 5.678$ .

Step-by-Step Solution:

Align the decimals:

$\begin{aligned} &12.430 \ +&\phantom{0}5.678 \ &\underline{<del>~</del>~~} \ &18.108 \end{aligned}$

Answer:

The sum is $18.108$ .

Q2: Subtract $17.84 - 9.567$ .

Step-by-Step Solution:

Align the decimals:

$\begin{aligned} &17.840 \ -&\phantom{0}9.567 \ &\underline{<del>~</del>~~} \ &\phantom{0}8.273 \end{aligned}$

Answer:

The difference is $8.273$ .

Q3: Add $6.251 + 14.78$ .

Step-by-Step Solution:

Align the decimals:

$\begin{aligned} &\phantom{0}6.251 \ +&14.780 \ &\underline{<del>~</del>~~} \ &21.031 \end{aligned}$

Answer:

The sum is $21.031$ .

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