Explore · MATH-5B-C09-L04-OPEN
Round 6.486 to the nearest hundredth.
Singapore Math 5B · Original independent course
Rounding Decimals
Watch for: Rounding the wrong place or always rounding up at 5 elsewhere.. Explain what the quantities mean before calculating.
Opening task
Prerequisite check
Before instruction · MATH-5B-C09-L04-PREREQ
Round 347 to the nearest ten.
Show worked answer (after attempting)
Answer: 350
The ones digit is 7, so the tens place rounds up.
Understand the idea
Round to whole, tenth, or hundredth with midpoint cases and explain the place retained. The essential earlier idea is: 4B whole-number rounding and decimal ordering.. The model below will always use the actual quantities from the worked problem. Check rounding the wrong place or always rounding up at 5 elsewhere when you explain your answer.
Three worked examples
Worked example 1 · MATH-5B-C09-L04-Q01
Round 6.485 to the nearest hundredth.
Solution: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.
Worked example 2 · MATH-5B-C09-L04-Q02
A board measures 2.75 m. Round to the nearest tenth of a meter.
Solution: 2.8 m
The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
Worked example 3 · MATH-5B-C09-L04-Q03
Round 9.964 to the nearest whole number; identify the digit examined.
Solution: 10
The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
Check understanding
1 · MATH-5B-C09-L04-Q04
Round 6.486 to the nearest hundredth.
Show worked answer (after attempting)
Answer: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.
2 · MATH-5B-C09-L04-Q05
A board measures 2.751 m. Round to the nearest tenth of a meter.
Show worked answer (after attempting)
Answer: 2.8 m
The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
3 · MATH-5B-C09-L04-Q06
Round 9.965 to the nearest whole number; identify the digit examined.
Show worked answer (after attempting)
Answer: 10
The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
Guided practice
1 · MATH-5B-C09-L04-Q07
Round 6.487 to the nearest hundredth.
Show worked answer (after attempting)
Answer: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.
2 · MATH-5B-C09-L04-Q08
A board measures 2.752 m. Round to the nearest tenth of a meter.
Show worked answer (after attempting)
Answer: 2.8 m
The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
3 · MATH-5B-C09-L04-Q09
Round 9.966 to the nearest whole number; identify the digit examined.
Show worked answer (after attempting)
Answer: 10
The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
4 · MATH-5B-C09-L04-Q10
Round 6.488 to the nearest hundredth.
Show worked answer (after attempting)
Answer: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.
Independent practice
1 · MATH-5B-C09-L04-Q11
A board measures 2.753 m. Round to the nearest tenth of a meter.
Show worked answer (after attempting)
Answer: 2.8 m
The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
2 · MATH-5B-C09-L04-Q12
Round 9.967 to the nearest whole number; identify the digit examined.
Show worked answer (after attempting)
Answer: 10
The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
3 · MATH-5B-C09-L04-Q13
Round 6.489 to the nearest hundredth.
Show worked answer (after attempting)
Answer: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.
4 · MATH-5B-C09-L04-Q14
A board measures 2.754 m. Round to the nearest tenth of a meter.
Show worked answer (after attempting)
Answer: 2.8 m
The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
5 · MATH-5B-C09-L04-Q15
Round 9.968 to the nearest whole number; identify the digit examined.
Show worked answer (after attempting)
Answer: 10
The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
6 · MATH-5B-C09-L04-Q16
Round 6.49 to the nearest hundredth.
Show worked answer (after attempting)
Answer: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.
7 · MATH-5B-C09-L04-Q17
A board measures 2.755 m. Round to the nearest tenth of a meter.
Show worked answer (after attempting)
Answer: 2.8 m
The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
8 · MATH-5B-C09-L04-Q18
Round 9.969 to the nearest whole number; identify the digit examined.
Show worked answer (after attempting)
Answer: 10
The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
Challenge and error analysis
1 · MATH-5B-C09-L04-ERR1
The assigned question is: “A board measures 2.758 m. Round to the nearest tenth of a meter.” A learner wrote: “I rounded the recorded value 2.758 without checking the next smaller decimal place and recorded 2.9 m.” 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: 2.8 m
The attempted reasoning or reported result does not satisfy the specified operation, units or geometric conditions. Correct mathematical result: 2.8 m. Recompute from the given data: The retained unit is 0.1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 2.8.
2 · MATH-5B-C09-L04-ERR2
The assigned question is: “Round 9.972 to the nearest whole number; identify the digit examined.” A learner wrote: “I rounded the recorded value 9.972 without checking the next smaller decimal place and recorded 11.” 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: 10
The attempted reasoning or reported result does not satisfy the specified operation, units or geometric conditions. Correct mathematical result: 10. Recompute from the given data: The retained unit is 1. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 10.
Exit check
Exit · MATH-5B-C09-L04-Q19
Round 6.491 to the nearest hundredth.
Show worked answer (after attempting)
Answer: 6.49
The retained unit is 0.01. Inspect the next smaller place; 5 or more rounds up. The positive half-up result is 6.49.