Name:    Lesson 4: Adding Decimals Using Mental Math

1.

Jasmine was training for a cross-country race. On the first day she ran 1.464 km. She  increased this distance by 0.673 km on the second day. Use mental math to estimate how far she ran on the second day.
 a. 2.000 km b. 2.200 km c. 2.100 km d. 2.300 km

2.

Use mental math to estimate how far Jasmine ran on both days combined.
 a. 3.500 km b. 3.600 km c. 3.700 km d. 3.400 km

3.

David was also training for a cross-country race. On the first day he ran 1.312 km and on the second day he ran 1.793 km. Use mental math to estimate the total distance he ran on both days combined.
 a. 3.100 km b. 3.000 km c. 3.200 km d. 3.300 km

4.

The diagram of a park is shown.

Use mental math to calculate the distance around the park. Which shows the estimate and the correct answer?
 a. 7.700 km and 6.742 km c. 6.000 km and 6.742 km b. 5.700 km and 6.742 km d. 6.700 km and 6.742 km

5.

Briana has a new puppy, Murphy. His birth mass was 0.514 kg. Briana tracked the increase in Murphy’s mass over the next 4 months and recorded it in the table shown.

 Month Increase in mass January 0.172 kg February 0.204 kg March 0.283 kg April 0.321 kg

Use mental math to calculate the total mass that Murphy gained over the 4 months. Which shows the estimate and the correct answer?
 a. 1.100 kg and 0.980 kg c. 0.900 kg and 0.980 kg b. 1.200 kg and 0.980 kg d. 1.000 kg and 0.980 kg

6.

Use mental math to calculate Murphy’s mass at the end of April. Which shows the estimate and the correct answer?
 a. 1.400 kg and 1.494 kg c. 1.500 kg and 1.494 kg b. 2.000 kg and 1.494 kg d. 1.600 kg and 1.494 kg

7.

Use mental math to calculate the sum. Which shows the estimate and the correct answer?
1.489 + 0.204
 a. 1.600 and 1.693 c. 1.800 and 1.693 b. 1.700 and 1.693 d. 1.500 and 1.693

8.

Use mental math to determine the missing number.
3.82 + a = 4
 a. 0.18 b. 0.2 c. 0.16 d. 0.08

9.

Use mental math to determine the missing number.
b + 9.025 = 10
 a. 0.875 b. 1.075 c. 0.075 d. 0.975

10.