Using Mental Math
Solve the following using mental math:
8.6 + 23.4 + 1.4 =
Answer: 33.4
Add the decimals using the rules:
0.02 + 0.89 =
Answer: 0.91
Subtract the decimals using the rules:
0.67 - 0.31
Answer: 0.36
Solve the following using mental math:
27 - 9.9 =
Answer: 17.1
Add the decimals using the rules:
0.34 + 0.34 =
Answer: 0.68
Subtract the decimals using rules:
8.71 - 0.4 =
Answer: 8.31
Solve the following using mental math:
13.5 + 5.7 + 36.5 =
Answer: 55.7
Add the decimals using the rules:
7.06 + 0.85 =
Answer: 7.91
Subtract the decimals using rules:
24.07 - 5.316 =
Answer: 18.754
Solve the following using mental math:
20.45 + 12.55 =
Answer: 33
Add the decimals using the rules:
98 + 3.79 =
Answer: 101.79
Subtract the decimals using rules:
51.92 - 28.003 =
Answer: 23.917
Solve the following using mental math:
205.4 - 99.7 =
Answer: 105.7
Solve the word problem:
Alberto ran 15.6 km on Monday, 12.8 km on Tuesday, and 6.5 km on Wednesday. Dennis ran 11.25 km on Monday, 14.6 km on Tuesday, and 8 km on Wednesday. Who ran farther?
Answer:
Alberto- 15.6 + 12.8 + 6.5 = 34.9
Dennis- 11.25 + 14.6 + 8 = 33.85
Alberto ran farther.
Solve the word problem:
Talia measured two strings. The green string was 2.37 cm long. The blue string was 4 cm long. How many centimeters longer was the blue string than the green string?
Answer: 4.00 - 2.37 = 1.63