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Great Inheritance Mathematics Term B · Original independent course

Multiplying by 0.1 or 0.01

Learning objective: Interpret multiplication by 0.1 and 0.01 as one-tenth or one-hundredth of a positive number.

Watch for: Believing multiplication must make a positive number larger.. Explain what the quantities mean before calculating.

Opening task

Explore · MATH-5B-C10-L03-OPEN

Find one tenth of 7.56 by calculating 7.56 × 0.1.

Prerequisite check

Before instruction · MATH-5B-C10-L03-PREREQ

What is 1/10 of 20?

Show worked answer (after attempting)
Answer: 2

20 ÷ 10 = 2.

Understand the idea

Interpret multiplication by 0.1 and 0.01 as one-tenth or one-hundredth of a positive number. The essential earlier idea is: 5A fraction multiplication and Chapter 9 decimal equivalence.. The model below will always use the actual quantities from the worked problem. Check believing multiplication must make a positive number larger when you explain your answer.

Three worked examples

Worked example 1 · MATH-5B-C10-L03-Q01

Find one tenth of 7.46 by calculating 7.46 × 0.1.

Scale compares original whole and chosen fraction.original7.46one fraction0.746

Solution: 0.746

0.1 is one tenth. Therefore 7.46 × 0.1 = 0.746, smaller than the starting positive amount.

Worked example 2 · MATH-5B-C10-L03-Q02

A container holds 4.5 L. What is one hundredth of this capacity?

Scale compares original whole and chosen fraction.original4.5one fraction0.045

Solution: 0.045 L

0.01 is one hundredth. Therefore 4.5 × 0.01 = 0.045, smaller than the starting positive amount.

Worked example 3 · MATH-5B-C10-L03-Q03

Explain whether 0.83 × 0.1 should be greater or less than 0.83 and calculate.

Scale compares original whole and chosen fraction.original0.83one fraction0.083

Solution: 0.083

0.1 is one tenth. Therefore 0.83 × 0.1 = 0.083, smaller than the starting positive amount.

Check understanding

1 · MATH-5B-C10-L03-Q04

Find one tenth of 7.56 by calculating 7.56 × 0.1.

Show worked answer (after attempting)
Answer: 0.756

0.1 is one tenth. Therefore 7.56 × 0.1 = 0.756, smaller than the starting positive amount.

2 · MATH-5B-C10-L03-Q05

A container holds 4.6 L. What is one hundredth of this capacity?

Show worked answer (after attempting)
Answer: 0.046 L

0.01 is one hundredth. Therefore 4.6 × 0.01 = 0.046, smaller than the starting positive amount.

3 · MATH-5B-C10-L03-Q06

Explain whether 0.93 × 0.1 should be greater or less than 0.93 and calculate.

Show worked answer (after attempting)
Answer: 0.093

0.1 is one tenth. Therefore 0.93 × 0.1 = 0.093, smaller than the starting positive amount.

Guided practice

1 · MATH-5B-C10-L03-Q07

Find one tenth of 7.66 by calculating 7.66 × 0.1.

Show worked answer (after attempting)
Answer: 0.766

0.1 is one tenth. Therefore 7.66 × 0.1 = 0.766, smaller than the starting positive amount.

2 · MATH-5B-C10-L03-Q08

A container holds 4.7 L. What is one hundredth of this capacity?

Show worked answer (after attempting)
Answer: 0.047 L

0.01 is one hundredth. Therefore 4.7 × 0.01 = 0.047, smaller than the starting positive amount.

3 · MATH-5B-C10-L03-Q09

Explain whether 1.03 × 0.1 should be greater or less than 1.03 and calculate.

Show worked answer (after attempting)
Answer: 0.103

0.1 is one tenth. Therefore 1.03 × 0.1 = 0.103, smaller than the starting positive amount.

4 · MATH-5B-C10-L03-Q10

Find one tenth of 7.76 by calculating 7.76 × 0.1.

Show worked answer (after attempting)
Answer: 0.776

0.1 is one tenth. Therefore 7.76 × 0.1 = 0.776, smaller than the starting positive amount.

Independent practice

1 · MATH-5B-C10-L03-Q11

A container holds 4.8 L. What is one hundredth of this capacity?

Show worked answer (after attempting)
Answer: 0.048 L

0.01 is one hundredth. Therefore 4.8 × 0.01 = 0.048, smaller than the starting positive amount.

2 · MATH-5B-C10-L03-Q12

Explain whether 1.13 × 0.1 should be greater or less than 1.13 and calculate.

Show worked answer (after attempting)
Answer: 0.113

0.1 is one tenth. Therefore 1.13 × 0.1 = 0.113, smaller than the starting positive amount.

3 · MATH-5B-C10-L03-Q13

Find one tenth of 7.86 by calculating 7.86 × 0.1.

Show worked answer (after attempting)
Answer: 0.786

0.1 is one tenth. Therefore 7.86 × 0.1 = 0.786, smaller than the starting positive amount.

4 · MATH-5B-C10-L03-Q14

A container holds 4.9 L. What is one hundredth of this capacity?

Show worked answer (after attempting)
Answer: 0.049 L

0.01 is one hundredth. Therefore 4.9 × 0.01 = 0.049, smaller than the starting positive amount.

5 · MATH-5B-C10-L03-Q15

Explain whether 1.23 × 0.1 should be greater or less than 1.23 and calculate.

Show worked answer (after attempting)
Answer: 0.123

0.1 is one tenth. Therefore 1.23 × 0.1 = 0.123, smaller than the starting positive amount.

6 · MATH-5B-C10-L03-Q16

Find one tenth of 7.96 by calculating 7.96 × 0.1.

Show worked answer (after attempting)
Answer: 0.796

0.1 is one tenth. Therefore 7.96 × 0.1 = 0.796, smaller than the starting positive amount.

7 · MATH-5B-C10-L03-Q17

A container holds 5 L. What is one hundredth of this capacity?

Show worked answer (after attempting)
Answer: 0.05 L

0.01 is one hundredth. Therefore 5 × 0.01 = 0.05, smaller than the starting positive amount.

8 · MATH-5B-C10-L03-Q18

Explain whether 1.33 × 0.1 should be greater or less than 1.33 and calculate.

Show worked answer (after attempting)
Answer: 0.133

0.1 is one tenth. Therefore 1.33 × 0.1 = 0.133, smaller than the starting positive amount.

Challenge and error analysis

1 · MATH-5B-C10-L03-ERR1

The assigned question is: “A container holds 5.3 L. What is one hundredth of this capacity?” A learner wrote: “5.3 × 0.01 = 0.153. I used this intermediate value to finish the assigned problem.” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.

Show worked answer (after attempting)
Answer: Correct result: 0.053 L

The attempted reasoning or reported result does not satisfy the specified operation, units or geometric conditions. Correct mathematical result: 0.053 L. Recompute from the given data: 0.01 is one hundredth. Therefore 5.3 × 0.01 = 0.053, smaller than the starting positive amount.

2 · MATH-5B-C10-L03-ERR2

The assigned question is: “Explain whether 1.63 × 0.1 should be greater or less than 1.63 and calculate.” A learner wrote: “1.63 × 0.1 = 1.163. I used this intermediate value to finish the assigned problem.” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.

Show worked answer (after attempting)
Answer: Correct result: 0.163

The attempted reasoning or reported result does not satisfy the specified operation, units or geometric conditions. Correct mathematical result: 0.163. Recompute from the given data: 0.1 is one tenth. Therefore 1.63 × 0.1 = 0.163, smaller than the starting positive amount.

Exit check

Exit · MATH-5B-C10-L03-Q19

Find one tenth of 8.06 by calculating 8.06 × 0.1.

Show worked answer (after attempting)
Answer: 0.806

0.1 is one tenth. Therefore 8.06 × 0.1 = 0.806, smaller than the starting positive amount.