Adding Decimals in 5th Grade Math

This video tutorial teaches how to add decimals by aligning decimal points and using placeholder zeros. It includes multiple examples, emphasizes checking answers for reasonableness through estimation, and highlights common mistakes. The video concludes with a mastery check to assess understanding.

What is the main rule to follow when adding decimals?

• Subtract the smaller number from the larger number

• Line up the decimal points

• Add from left to right

• Ignore the decimal points

Why is it important to use placeholder zeros when adding decimals?

• To ensure all place values are aligned

• To make the numbers look bigger

• To make the addition faster

• To avoid using a calculator

What should you do after adding the numbers in a decimal addition problem?

• Round the answer to the nearest whole number

• Check if the answer is reasonable using estimation

• Multiply the answer by 10

• Subtract the smaller number from the larger number

In the second example, what is the estimated sum of 15 and 10?

• 30

• 35

• 25

• 20

Where does the decimal point go in a whole number like 103?

• After the number

• In the middle of the number

• Before the number

• There is no decimal point in whole numbers

What should you do if your answer does not match the estimation?

• Recheck your addition and alignment of decimals

• Multiply the answer by 2

• Ignore it and move on

• Change the numbers to match the estimation

In the third example, what is the estimated sum of 103 and 18?

• 100

• 110

• 120

• 130

What is a common mistake to avoid when adding decimals?

• Lining up the numbers without aligning the decimal points

• Using a calculator

• Using too many placeholder zeros

• Adding from left to right

In the fourth example, what is the estimated sum of 57 and 5?

• 50

• 55

• 60

• 62

What is the final step after adding decimals?

• Subtract the smaller number from the larger number

• Bring the decimal point straight down in the answer

• Multiply the answer by 10

• Round the answer to the nearest whole number