WALT:

Adding and Subtracting Decimal Numbers

Adding Decimals

1. Write down the numbers, one under the other, with the decimal points lined up
2. Put in zeros so the numbers have the same length and easier to add
3. Then add using column addition, remembering to put the decimal point in the answer

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Adding Decimals

Example: 1.452 + 1.3 = ????

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1. Line the decimal points up: 1.452� + 1.3

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• Add in zeros 1.452� + 1.300

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• Add numbers together 1.452� + 1.300

2.752

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Zeros are important - they tell us there is NO VALUE in that decimal place

Adding Decimals

Make a new slide, show your working out

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1. 36.88 + 30.11 =
2. 47.52 + 21.46 =
3. 23.43 + 15.46
4. 85.36 + 11.14

5) 56.02 + 32.55

6) 75.24 + 96.35

Subtracting Decimals

Example: 7.368 - 1.15 = ????

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• Line the decimal points up: 7.368� - 1.15

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• Add in zeros 7.368

- 1.150

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• Add numbers together 7.368� - 1.150

6.218

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TIP: � Add the answer and the number subtracted � e.g. 6.218 - 1.150 = 7.368 � This means the answer 6.218 is correct!!

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Zeros are important - they tell us there is NO VALUE in that decimal place

Subtracting Decimals

Make a new slide, show your working out

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1. 98.46 - 24.31
2. 58.69 - 47.23
3. 85.39 - 22.27
4. 69.89 - 52.69
5. 89.78 - 86.45
6. 192.94 - 61.42

Word Problems with Decimals

1. A restaurant ordered 6.1 kilograms of pasta. The next night, the restaurant ordered 1.2 kilograms of pasta. How much pasta is did they order in total?

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• It rained 4.7 centimetres on Monday and 1.8 centimetres on Tuesday. How much did it rain on Monday and Tuesday altogether?

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• The school ordered 5.3 kilograms of sugar. The next week, the school used 1.5 kilograms of it baking cakes for the garage sale. How much sugar does the school have left?

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• Alisha bought 0.2 kilograms of bananas and 0.8 kilograms of oranges. How much fruit did she buy in all?

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Your turn!!!

• Create a new slide with your own set of �10 decimal number problems for a buddy to answer
• Include addition and subtraction problems�
• Use numbers with 2 decimal places e.g. 2.56

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