True/False
Adding Decimals
Adding Decimals 2
Place Value
Miscellaneous
100

When adding decimals, you always include the decimals.

True

100

43.14 + 5.12 = 

What is 48.26?

100

Add the decimals 43.28 + 31.45

What is 74.73

100

What number is in the hundredths place


45.67

What is 7?

100

A backpack costs $18.75, a lunchbox costs $12.40, and a water bottle costs $5.95. Estimate the total cost using rounding to the nearest whole number.

18.75+12.40+5.95

about $37

$19+$12+$6=37

200

When adding  decimals, you always put the longer number on top.

What is false?

200

114.73 + 68.1=

What is 182.83?

200

Add the decimals 0.724 + 6.458

What is 7.182

200

What number is in the ones place.


23.09

What is 3?

200

Lila wants to buy a toy that costs $37.50. She estimates the cost as $40 before putting money in her wallet. Why is this a smart strategy?

 it helps make sure she has enough money to buy the toy?

300
Sum is the numbers you add together.

False. Sum is the answer to an addition problem

300

3.529 + 1822.55=

What is 1826.079?

300

Add the Decimals 1.325 + 0.081

What is 1.406

300

What number is in the tenths place.


9.12

What is 1?

300

A game costs $24.99. Josh estimates the cost as $20. Is Josh overestimating or underestimating?

What is underestimating?

400

When adding decimals, you ignore the decimal points.

False

400

Jim wants to buy the newest game. He wants to make sure he takes enough money with him. 

Should he overestimate the total cost or underestimate?

Jim should overestimate the total cost because he wants to make sure he has enough money to buy the game. If he underestimates, he might not bring enough money and may not be able to buy it.

400

43.234+12.953=

56.187

400

What number is in the tens place.


76.9

What is 7?

500

142.21+140=143.61

Justify your answer

False! They did not align the decimals and place values. 

The correct answer is 

142.21+140=282.21

500

Jen went to the store and bought three things

Chips $5.95

Fruit $22.36

a toy $ 65

Estimate about how much money she should bring with her.

Original Prices

  • Chips: $5.95
  • Fruit: $22.36
  • Toy: $65.00

1. Rounding

  • $5.95 → $6
  • $22.36 → $22
  • $65.00 → $65

Estimated total:
$6 + $22 + $65 = $93

2. Front-End Estimation

  • $5.95 → $5
  • $22.36 → $20
  • $65.00 → $60

Estimated total:
$5 + $20 + $60 = $85

3. Compatible Numbers

Students may choose different compatible numbers as long as they are reasonable and easy to add.

Example 1

  • $5.95 → $6
  • $22.36 → $24
  • $65.00 → $65

$6 + $24 + $65 = $95

Example 2

  • $5.95 → $5
  • $22.36 → $25
  • $65.00 → $65

$5 + $25 + $65 = $95

Example 3

  • $5.95 → $10
  • $22.36 → $20
  • $65.00 → $70

$10 + $20 + $70 = $100

Possible Student Answers

  • Rounding: About $93
  • Front-End: About $85
  • Compatible Numbers: About $95 or $100 depending on the numbers chosen.
500

77,777.7 + 359.88

78,137.58

500

When you read a number with a decimal, what do you say when you see the decimal?

AND

500

Jess is buying supplies for a class project:

  • Poster board: $12.95
  • Markers: $8.75
  • Stickers: $4.99
  • Glue: $2.50

What is the total cost of the supplies?

$29.19

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