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Lesson 1: Mental Addition Strategies with Decimals — Practice Questions

  1. 1. Use the partial sums method to find the sum of $4.26 + 1.53$. What is the total sum? ___

  2. 2. When finding the sum of $5.67 + 2.18$ using partial sums, what is the partial sum from adding the hundredths place values?

    • A. 0.15
    • B. 0.70
    • C. 7.00
    • D. 0.85
  3. 3. Use the partial sums method to calculate $8.9 + 3.5$. What is the final answer? ___

  4. 4. When adding $7.8 + 4.15$ using partial sums, what is the partial sum from the tenths place?

    • A. 0.80
    • B. 0.90
    • C. 1.30
    • D. 0.05
  5. 5. Use the partial sums strategy to find the sum of $24.6 + 8.5$. The total sum is ___.

  6. 6. A tailor has two rolls of fabric. One roll is 3.45 meters long, and the second is 2.8 meters long. The total length of fabric is ___ meters.

  7. 7. Leo adds the lengths of two ropes, 5.4 m and 12.31 m. He incorrectly calculates the total as 12.85 m. What was his most likely error?

    • A. He subtracted the numbers.
    • B. He treated 5.4 as 0.54.
    • C. He treated 12.31 as 1.231.
    • D. He rounded the numbers before adding.
  8. 8. A chemist mixes three solutions. She uses 0.75 liters of solution A, 1.2 liters of solution B, and 0.48 liters of solution C. The total volume is ___ liters.

  9. 9. In a video game, Aisha has 458 points. She finds a power-up that adds 25.5 bonus points to her score. What is her new total score? ___ points.

  10. 10. Which of the following expressions equals 24.75?

    • A. $12.7 + 12.05$
    • B. $24 + 0.7$
    • C. $20.5 + 4.05$
    • D. $14.75 + 9$