Subtraction with decimals (standard algorithm)

Decimal operations using the standard algorithm

Exit Ticket

Do Now!

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When you have finished flip over your paper.

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You have 3 minutes to:

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-Complete the Do Now!

-When you are finished flip over your paper.

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542.78

7

Problem 3:

5

What number is in the tenths place?

What number is in the hundreds place?

What number is in the ones place?

What number is in the hundredths place?

2

8

Holly and Keisha both play basketball. Holly scores an average of 18.34 points per game and Keisha scores an average of 16.97 points per game. How many more points per game does Holly average than Keisha?

Problem 2:

Standard algorithm

Explain your thinking

Standard algorithm

Explain your thinking

18.34-16.97

I subtract.

I want to subtract 16.97 from 18.34

I line up the decimals.

I bring down the decimal point to the answer.

Holly scores 1.37 more average points per game than Keisha.

Maria and Connor were both sick. Maria had a temperature of 102.12 degrees. Connor had a temperature that was 1.38 degrees less. What was Connor's temperature in degrees?

Standard algorithm

Explain your thinking

Standard algorithm

Explain your thinking

102.12-1.38

I want to subtract 1.38 from 102.12

I subtract.

I line up the decimal point.

I bring down the decimal point to the answer.

Connor's temperature was 100.74 degrees.

Today's objective:

Do I add or subtract?

Subtract

If there are 12 eggs in a carton and Arman takes 4 eggs out, how many eggs are left in the carton?

Problem 4:

Subtract

Sara has 55 blocks. 29 are eaten by a hippopotamus. How many blocks will Sara have now?

Students will be able to explain their thinking when subtracting multi-digit decimals using the standard algorithm.

Add

Trisha has 5 bananas. She gets 3 more from Joyce. How many bananas does Trisha have in all?

Subtract

Philip weighs 89 pounds. Elizabeth weighs 65 pounds. How much heavier is Philip than Elizabeth?

Andrew weighs 83.42 pounds. His twin brother, Christopher, weighs 87.12 pounds. How many more pounds does Christopher weigh?

Problem 1:

Standard algorithm

Explain your thinking

87.12-83.42

I want to subtract 83.42 from 87.12

I line up the decimal points

I bring the decimal point down

I subtract.

Christopher weighs 3.70 more pounds.

The average length of the humpback whale is 13.7 m. The average length of the killer whale is 6.85 m. How much longer is the humpback whale than the killer whale?

Standard algorithm

Explain your thinking

Standard algorithm

13.7 - 6.85

I need to subtract 6.85 from 13.7

I subtracted.

I lined up the decimals so that I can subtract.

I added a zero as a placeholder.

I brought down the decimal for my answer.

Humpback whales are 6.85 m longer than killer whales.