Adding, Subtracting, and Comparing Decimals
Adding, Subtracting, and Comparing Decimals
Adding and subtracting decimals follows the same column-alignment logic as whole numbers — the key rule is to line up the decimal points so that you are adding digits with the same place value. Once the points are aligned, the procedure is identical to whole-number addition and subtraction.
Comparing decimals is equally straightforward. Append trailing zeros so both numbers have the same number of decimal places, then compare digit by digit from left to right, just as you would with whole numbers.
This lesson will strengthen your confidence with these foundational operations, preparing you for the multiplication and division of decimals in the next lesson.
Align the decimal points, pad with trailing zeros, then add/subtract as with whole numbers.
$12.7 + 3.045$
$$12.700 + 3.045 = 15.745$$
$50.03 - 8.174$
$$50.030 - 8.174 = 41.856$$
$100 - 37.85$
$$100.00 - 37.85 = 62.15$$
Comparing Decimals
- Align decimal points.
- Compare digit by digit, left to right.
- Trailing zeros don't change value: $3.5 = 3.50$.
Which is greater: $0.45$ or $0.405$?
$0.450$ vs $0.405$: hundredths $5 > 0$. So $0.45 > 0.405$.
Order: $0.7$, $0.07$, $0.71$, $0.17$.
$$0.07 < 0.17 < 0.70 < 0.71$$
Practice Problems
Show Answer Key
1. $18.23$
2. $13.12$
3. $1.005$
4. $44.55$
5. $<$ ($3.09 < 3.90$)
6. $10.955$
7. $24.925$
8. $1.005 < 1.05 < 1.5 = 1.50$
9. $7.953$
10. $0.011$
11. $\$14.03$
12. $\$11.64$
13. $<$
14. $10.028$
15. $999.999$