Question 1: Calculate the sum of 12.345 and 7.89, rounded to 2 decimal places.

Answer: 20.24

Question 2: Add 3.456 and 2.789, then round the result to 2 decimal places. Write your answer.

Answer: 6.24

Question 3: Add 15.678 and 4.321. Round to 2 decimal places.

Answer: 20.00

Question 4: Calculate 9.876 + 0.124, rounded to 2 decimal places.

Answer: 10.00

Question 1: A calculator displays 23.456 + 7.89. A student reports the answer as 31.35 after rounding to 2 decimal places. Is this correct? Explain your reasoning.

Answer: No, the correct sum is 31.35 when rounded properly; however, if the student rounded prematurely, errors could occur.

Question 2: Explain why adding 2.345 and 3.2 and then rounding might lead to a different result compared to rounding each number first before addition.

Answer: Because intermediate rounding can cause small discrepancies, leading to less precise final answers.

Question 3: If a student adds 4.567 and 2.34 and reports 6.91 after rounding, is this accurate? Show your working.

Answer: No, the exact sum is 6.907. Rounded to 2dp, it should be 6.91, so the student's answer is correct.

Question 1: A shop sells 3 items priced at £12.49, £8.75, and £5.99. Calculate the total cost, rounded to 2 decimal places.

Answer: 27.23

Question 2: A car journey covers 123.456 km. The driver reports the distance as 123.46 km after rounding to 2 decimal places. Is this correct? Explain.

Answer: Yes, since 123.456 rounded to 2 decimal places is 123.46 km.

Question 1: Add 0.3333 and 0.6667, then round to 2 decimal places. What is the importance of accurate decimal places in this context?

Answer: The sum is 1.00; precise rounding is crucial in financial or measurement contexts to avoid errors.

Question 2: Construct a decimal addition problem where premature rounding leads to an incorrect final answer. Provide the calculation and explanation.

Answer: Adding 1.234 and 2.345 and rounding intermediate results can cause inaccuracies. For example, rounding 1.234 to 1.23 and 2.345 to 2.35 before addition yields 3.58, which is less precise than summing and then rounding (which gives 3.58 in this case, but errors grow with more complex calculations).

Question 1: A student added 7.89 and 3.456 and reported 11.34 after rounding. Find the mistake and correct the answer.

Answer: The correct sum is 11.346, which rounds to 11.35, not 11.34.

Question 2: A calculator shows 4.567 + 5.432. The student reports 10.00 after rounding. Is this correct? Why or why not?

Answer: No, the exact sum is 10.0, which rounds to 10.00; the student’s answer is correct but they should clarify rounding process.