5th Grade Multiplying and Dividing Decimals Worksheet Solutions (PDF)

This answer key gives a full worked solution for each of the 20 decimal problems. Each solution shows the whole-number step, the decimal-point step, and the final answer in bold. Compare the steps with your own work to find where a mistake started.
Grade 5 · Common Core State Standards: 5.NBT.B.7
Exercise 1 – Tenths times a whole number
Ignore the decimal points and multiply: \(7 \times 6 = 42\).
The factors have 1 and 0 decimal places, so the product has 1 + 0 = 1 decimal place: \(4.2\).
\(4.2\)
Exercise 2 – Hundredths times a whole number
Ignore the decimal points and multiply: \(6 \times 7 = 42\).
The factors have 2 and 0 decimal places, so the product has 2 + 0 = 2 decimal places: \(0.42\).
\(0.42\)
Exercise 3 – Product from a model
6 columns shaded blue show 0.6. 3 rows shaded orange show 0.3.
The overlap is \(6 \times 3 = 18\) squares, and each square is 0.01.
\(0.6 \times 0.3 = 0.18\)
Exercise 4 – Decimal times tenths
Ignore the decimal points and multiply: \(42 \times 5 = 210\).
The factors have 1 and 1 decimal places, so the product has 1 + 1 = 2 decimal places: \(2.10\).
Dropping the extra zero gives \(2.1\).
\(2.1\)
Exercise 5 – Two decimal factors
Ignore the decimal points and multiply: \(36 \times 24 = 864\).
The factors have 1 and 1 decimal places, so the product has 1 + 1 = 2 decimal places: \(8.64\).
\(8.64\)
Exercise 6 – Hundredths and tenths
Ignore the decimal points and multiply: \(25 \times 4 = 100\).
The factors have 2 and 1 decimal places, so the product has 2 + 1 = 3 decimal places: \(0.100\).
Dropping the extra zero gives \(0.1\).
\(0.1\)
Exercise 7 – Zeros in the product
Ignore the decimal points and multiply: \(5 \times 2 = 10\).
The factors have 2 and 1 decimal places, so the product has 2 + 1 = 3 decimal places: \(0.010\).
Dropping the extra zero gives \(0.01\).
\(0.01\)
Exercise 8 – Divide tenths by a whole number
Divide as with whole numbers: \(48 \div 4 = 12\).
Put the decimal point so the quotient has 1 decimal place: \(1.2\).
\(1.2\)
Exercise 9 – Divide hundredths by a whole number
Divide as with whole numbers: \(756 \div 6 = 126\).
Put the decimal point so the quotient has 2 decimal places: \(1.26\).
\(1.26\)
Exercise 10 – Quotient less than 1
Divide as with whole numbers: \(72 \div 9 = 8\).
Put the decimal point so the quotient has 2 decimal places: \(0.08\).
\(0.08\)
Exercise 11 – Keep dividing with zeros
Write 9.3 as 9.30 so the division can end.
Divide as with whole numbers: \(930 \div 5 = 186\).
Put the decimal point so the quotient has 2 decimal places: \(1.86\).
\(1.86\)
Exercise 12 – Divide by tenths
Multiply both numbers by 10 so the divisor is a whole number: \(6.3 \times 10 = 63\) and \(0.9 \times 10 = 9\).
Now divide: \(63 \div 9 = 7\).
\(7\)
Exercise 13 – Divide by hundredths
Multiply both numbers by 100 so the divisor is a whole number: \(1.44 \times 100 = 144\) and \(0.12 \times 100 = 12\).
Now divide: \(144 \div 12 = 12\).
\(12\)
Exercise 14 – Decimal divided by decimal
Multiply both numbers by 10 so the divisor is a whole number: \(0.72 \times 10 = 7.2\) and \(0.4 \times 10 = 4\).
Now divide: \(7.2 \div 4 = 1.8\).
\(1.8\)
Exercise 15 – Apples at the market
Multiply the weight by the price per pound: \(3.5 \times 1.8\).
Ignore the decimal points and multiply: \(35 \times 18 = 630\).
The factors have 1 and 1 decimal places, so the product has 1 + 1 = 2 decimal places: \(6.30\).
Dropping the extra zero gives \(6.3\).
The product 6.3 means $6.30.
The apples cost $6.30.
Exercise 16 – Ribbon for bows
Ribbon used: \(0.65 \times 12\).
\(65 \times 12 = 780\), and 2 decimal places gives \(7.80 = 7.8\).
Ribbon left: \(10 – 7.8 = 2.2\).
2.2 yards are left.
Exercise 17 – Unit price
Divide the total cost by the number of pounds: \(14.40 \div 1.8\).
Multiply both numbers by 10 so the divisor is a whole number: \(14.40 \times 10 = 144\) and \(1.8 \times 10 = 18\).
Now divide: \(144 \div 18 = 8\).
Trail mix costs $8 per pound, or $8.00.
Exercise 18 – Movie tickets
Total cost: \(8.75 \times 4\).
\(875 \times 4 = 3{,}500\), and 2 decimal places gives \(35.00\).
She pays $40. Change: \(40 – 35 = 5\).
Priya gets $5.00 in change.
Exercise 19 – Trail markers
Divide the trail length by the length of one section: \(5.4 \div 0.45\).
Multiply both numbers by 100 so the divisor is a whole number: \(5.4 \times 100 = 540\) and \(0.45 \times 100 = 45\).
Now divide: \(540 \div 45 = 12\).
The trail has 12 equal sections.
Exercise 20 – Garden soil
Area: \(3.6 \times 2.5\).
\(36 \times 25 = 900\), and 2 decimal places gives \(9.00 = 9\) square feet.
Cost: \(9 \times 0.75\).
\(9 \times 75 = 675\), and 2 decimal places gives \(6.75\).
The area is 9 square feet and the soil costs $6.75.
All Grade 5 chapters: Grade 5 math.
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