Virginia SOL Math / Grade 5 / Computation & Estimation
Add, Subtract, Multiply & Divide Decimals
What you'll learn
- Add and subtract decimals through thousandths
- Multiply and divide decimals by whole numbers
- Estimate and solve decimal problems in context
Words to know
- Decimal point —
- the dot separating whole numbers from parts
- Tenth —
- one of 10 equal parts, the first place after the point
- Hundredth —
- one of 100 equal parts, the second place after the point
- Align —
- line up decimal points so places match
- Estimate —
- a close, reasonable answer using rounding
Why it matters We use decimals for money and measurement every day, so computing with them helps us make purchases and measure precisely.
Worked examples
Model ItI do
Find 3.6 + 2.45.
Line up the decimal points and write 3.60 above 2.45. Add each place to get 6.05, so 3.6 + 2.45 = 6.05.
Try It TogetherWe do
Find 4.2 x 3.
Multiply as if there were no point: 42 x 3 = 126. Since 4.2 has one decimal place, place the point one spot from the right to get 12.6.
Now YouYou do
Find 9.6 divided by 4.
Divide as with whole numbers and keep the decimal point lined up in the quotient. Check your answer in the back of this chapter.
Practice
Mastered 0 of 11
Warm-up
Ease in with the basics.
1.Find 2.4 + 1.5.
2.Find 5.6 - 1.2.
3.Find 1.2 x 3.
On Level
The core Quick Check from the book.
1.Find 5.3 + 1.8.
2.Find 7.5 - 2.9.
3.Find 2.5 x 4.
4.Find 6.4 divided by 2.
5.A pen costs 1.25 dollars. What do 3 pens cost?
Challenge
Stretch your thinking.
1.Find 12.05 + 3.9 + 0.375.
2.Find 15.6 divided by 4.
3.A ribbon is 8.4 meters long. It is cut into 6 equal pieces. How long is each piece?