Decimal Addition/Subtraction - ISEE Lower Level Mathematics Achievement

1. What is $0.8 - 0.125$?

   $0.675$. Align decimals: $0.800 - 0.125$; subtract thousandths with borrowing to get $0.675$.

2. What is $100.0 - 0.75$?

   $99.25$. Align decimals: $100.00 - 0.75$; subtract hundredths with borrowing from units for $99.25$.

3. What is $1.01 - 0.99$?

   $0.02$. Align decimals: $1.01 - 0.99$; subtract hundredths with borrowing for $0.02$.

4. What is $4.305 + 0.07$?

   $4.375$. Align decimals: $4.305 + 0.070$; add thousandths, resulting in a carryover to hundredths for $4.375$.

5. What is $1.2 - 0.35$?

   $0.85$. Align decimals: $1.20 - 0.35$; subtract with borrowing in the hundredths place for $0.85$.

6. What is $0.500 - 0.275$?

   $0.225$. Align decimals: $0.500 - 0.275$; subtract thousandths first, borrowing as needed for $0.225$.

7. What is $8.06 + 0.9$?

   $8.96$. Align decimals: $8.06 + 0.90$; add columns from right to left to get $8.96$.

8. What is $0.001 + 0.010$?

   $0.011$. Align decimals: $0.001 + 0.010$; add thousandths and hundredths to obtain $0.011$.

9. Find the value of $0.06 + 0.06 + 0.06$.

   $0.18$. Add hundredths: three $0.06$ values align and sum to $0.18$ with carrying.

10. What is $10.2 - 3.85$?

    $6.35$. Align decimals: $10.20 - 3.85$; subtract column by column with borrowing to obtain $6.35$.

11. What is $6.1 - 2.009$?

    $4.091$. Align decimals: $6.100 - 2.009$; subtract with borrowing across places to get $4.091$.

12. What is $7.5 - 7.5$?

    $0$. Align decimals: $7.5 - 7.5$; subtracting identical values results in zero.

13. What is $3.000 - 0.999$?

    $2.001$. Align decimals: $3.000 - 0.999$; subtract thousandths with borrowing from units to yield $2.001$.

14. What is $2.48 + 0.52$?

    $3.00$. Align decimals: $2.48 + 0.52$; add hundredths and tenths, carrying to units for $3.00$.

15. What is $0.7 + 0.08$?

    $0.78$. Align decimals: $0.70 + 0.08$; add tenths and hundredths separately to reach $0.78$.

16. Identify the first step to subtract decimals accurately in vertical form.

    Write numbers so the decimal points are aligned. Aligning decimal points vertically ensures corresponding place values are matched for accurate borrowing and subtraction.

17. What is $0.04 + 0.009$?

    $0.049$. Align decimals: $0.040 + 0.009$; add thousandths, carrying to hundredths for $0.049$.

18. What is $3.7 + 2.45$?

    $6.15$. Align decimals: $3.70 + 2.45$; add from right, resulting in $6.15$ after carrying over where needed.

19. What is $12.34 + 0.006$?

    $12.346$. Align decimals: $12.340 + 0.006$; add thousandths to obtain $12.346$.

20. State the rule for aligning place values when adding or subtracting decimals.

    Line up decimal points; add or subtract by columns. Aligning decimal points ensures that digits in the same place values (units, tenths, hundredths, etc.) are added or subtracted correctly.

21. What is the rule for adding zeros to decimals before adding or subtracting?

    You may append trailing zeros to match decimal places. Appending trailing zeros equalizes the number of decimal places, allowing proper alignment and accurate column-wise addition or subtraction.

22. What is $9.999 + 0.001$?

    $10.000$. Align decimals: $9.999 + 0.001$; add thousandths, carrying over to units for $10.000$.

23. What is $15.08 - 9.7$?

    $5.38$. Align decimals: $15.08 - 9.70$; subtract with borrowing in tenths and units for $5.38$.

24. What is $5.00 - 2.38$?

    $2.62$. Align decimals: $5.00 - 2.38$; subtract with borrowing from the units place to yield $2.62$.

25. What is $0.3 + 0.3 + 0.3$?

    $0.9$. Add tenths: three instances of $0.3$ sum to $0.9$ by aligning and adding.

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