Decimals are numbers with parts less than 1, like 0.5 or 3.14.
Adding decimals is just like adding whole numbers. We use column form.
Let's learn with some examples.
43.36 + 35.21 = ?
To add decimals, first write the numbers in column form.
Line up the decimal points one above the other.
Start adding from the rightmost (👉) place value, the hundredths place.
We continue on to the next place value - the tenths place digits.
Then we add the Ones and Tens place digits after.
Tip: Don't forget to write the decimal point in the final answer between the Ones and the Tenths.
The answer is:
43.36 + 35.21 = 78.57
Great work.
Lets try another example:
113.712 + 365.94 = ?
First, arrange the numbers in column form.
The first addend has three decimal places, while the second addend has two decimal places.
To make it easy to add the numbers, we add a 0 after 4 in the second addend.
Then we can start adding.
We had to do some regrouping in the Tenths place.
Our answer is...
113.712 + 365.94 = 479.652
Great job learning how to add decimals.
Subtracting decimals is just the same as subtracting whole numbers.
Let's subtract these decimals:
489.32 - 315.01 = ?
Start by writing the numbers in column form.
We start subtracting at the rightmost (👉) place value.
We continue subtracting in the Tenths place.
Now, we add all the way up to the leftmost digit, which is the Hundreds place.
We've got our answer.
Let's try another example:
1,295.43 - 762.192 = ?
As always, we arrange these numbers in column, or vertical, form.
Line up the decimal points above each other. This lines up the place values.
The number at the top has two decimal places, while the number at the bottom has three.
To make the number of decimals the same in both numbers, we add a 0 after 3 the top number.
Then we start subtracting from the Thousandths place.
2 is bigger than 0, so we need to regroup.
We cannot subtract 9 from 2. So we also have to regroup in the Hundredths place as well.
Then we continue subtracting in the other place values.
Excellent.
Let's solve one more example together:
340 - 49.55 = ?
We line up the numbers in column, or vertical, form.
The first number has no decimal.
We add a decimal point and two placeholder zeros to 340 to match the number of decimals in the bottom number.
Then we start subtracting. It looks like we need to regroup in all the place values.
Now, we're done.
340 - 49.55 = 290.45 ✅
Great job in learning how to add and subtract decimals. 👏
Now, practice adding and subtracting decimals on your own. You can do it! Believe in yourself.
Practice Tip: draw any carry overs right on the practice questions with your finger or mouse. The question is a scratchpad.