Nathan works out 23 × 12.4 without a calculator - OCR - GCSE Maths - Question 3 - 2017 - Paper 1
Question 3
Nathan works out 23 × 12.4 without a calculator.
This is Nathan’s working.
10 × 12.4 = 12.40
20 × 12.4 = 24.80
3 × 12.4 = 37.2
23 × 12.4 = 24.80 + 37.2 = 62
Natha... show full transcript
Worked Solution & Example Answer:Nathan works out 23 × 12.4 without a calculator - OCR - GCSE Maths - Question 3 - 2017 - Paper 1
Step 1
Explain the error that Nathan has made
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Answer
Nathan made an error when multiplying 12.4 by 10. He did not move the decimal point to the right properly. Instead of calculating 10 × 12.4 as 124.0, he mistakenly recorded it as 12.40.
This indicates that he has added an extra zero and misaligned the decimal point.
Step 2
Work out the correct answer
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Answer
To find the correct value of 23 × 12.4, we should first calculate:
