Michaela meant to work out the answer to \ 50.45 - 0.4 \ on her calculator, but she made a mistake and got the answer \ 20.18 \ Which of these is most likely to have been her mistake?
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\text{pressing } + \text{ instead of } -
\text{pressing } 40 \text{ instead of } 0.4
\text{missing out one of the decimal points}
\text{pressing } \div \text{ instead of } -
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Primary Mathematics Challenge 2018 (2018)
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