Adding with Significant Digits

Emily and Benjamin are at a carnival, and they want to buy a giant cotton candy that costs 15.25 tickets and a fun ride that costs 1.3 tickets. How many tickets do they need in total?

• 16.5

• 16.55

• 16.6

• 16.50

Answer explanation

To add 15.25 and 1.3, align the decimal points: 15.25 + 1.30 = 16.55. Rounding to one decimal place gives 16.6, which is the correct answer.

Match the following scenarios with the correct amount Kiara actually pays.

• Kiara buys candies worth 10.5 dollars with a discount of 2.8 dollars.

• 7.8

• Kiara buys candies worth 10.5 dollars with a discount of 2.70 dollars.

• 7.7

• Kiara buys candies worth 10.5 dollars with a discount of 2.7 dollars.

• 7.75

• Kiara buys candies worth 10.5 dollars with a discount of 2.75 dollars.

• 7.80

Answer explanation

To solve 10.5 - 2.75, align the decimal points: 10.50 - 2.75 = 7.75. Thus, the correct answer is 7.75.

Match the following numbers with their sums.

• 9.87 + 3.002 = ?

• 12.872

• 9.5 + 3.4 = ?

• 12.870

• 9.870 + 3.000 = ?

• 12.9

• 9.87 + 3.0020 = ?

• 12.87

Answer explanation

To solve 9.87 + 3.002, align the decimal points: 9.870 + 3.002 = 12.872. Rounding to two decimal places gives 12.87, which matches the correct answer choice.

Zoey and Samuel are playing a math game. Zoey asks Samuel: "If you have 0.25 candies and I give you 0.0028 more, how many candies do you have now?"

• 0.253

• 0.2528

• 0.250

• 0.25

Answer explanation

To add 0.25 and 0.0028, align the decimal points: 0.2500 + 0.0028 = 0.2528. Thus, the correct answer is 0.2528.

Rohan and Grace are at a math fair, and they stumble upon a puzzle: 4.007 + 1.23 = (a)  

• 5.24
• 5.237
• 5.2
• 5.240

Answer explanation

To add 4.007 and 1.23, align the decimal points: 4.007 + 1.230 = 5.237. The correct answer is 5.237, as it includes all significant digits.

Emma and Samuel are at a candy store. Emma has $21.99 and buys a candy for $1.258. She has (a)   money left.

• 20.73
• 20.7
• 20.732
• 20.73

Answer explanation

To solve 21.99 - 1.258, perform the subtraction: 21.99 - 1.258 = 20.732. Rounding to two decimal places gives 20.73, which matches the correct answer choice.

During a math challenge, Daniel and Sofia are trying to solve this puzzle: What is 83.01 - 0.103?

• 82.91

• 82.9

• 82.907

• 82.91

Answer explanation

To solve 83.01 - 0.103, align the decimal points: 83.010 - 0.103 = 82.907. Rounding to two decimal places gives 82.91, which matches the correct answer choice.

Match the following sums with their results.

• 3.45 + 1.78 = ?

• 5.2

• 3.4 + 1.8 = ?

• 5.23

• 3.45 + 1.78 = ?

• 5.230

• 3.2 + 2.02 = ?

• 5.22

Answer explanation

To solve 3.45 + 1.78, align the decimal points and add: 3.45 + 1.78 = 5.23. However, rounding to one decimal place gives 5.2, which is the correct answer choice.

James and Liam are playing a math game. James challenges Liam to solve this: What is 5.3 - 0.255?

• 5.04

• 5.05

• 5.045

• 5.1

Answer explanation

To solve 5.3 - 0.255, align the decimal points: 5.300 - 0.255 = 5.045. Thus, the correct answer is 5.045.

Match the following numbers with their sums.

• 100.0 + 1.00 = ?

• 101.00

• 99.0 + 1.99 = ?

• 101

• 100.0 + 1.0 = ?

• 101.0

• 100.0 + 1 = ?

• 100.99

Answer explanation

To solve 100.0 + 0.99, simply add the two numbers. The result is 100.99, which is equivalent to 101.0 when rounded to one decimal place. Therefore, the correct answer is 101.0.