Agnes Tung's answer to riz's Primary 5 Maths Decimals Singapore question.

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Agnes Tung
Agnes Tung's answer
21 answers (A Helpful Person)
1st
For the first digit, he can choose one digit out from 2, 4,7 or 8. Hence he has 4 choices.
For the second digit, he was left with 3 choices as one digit has been selected and there are no repeatation of digits.
For the last digit, he was left with 2 choices as two digits had been selected.
Total combinations of digits =4*3*2=24
Since, he already tried 2 combination,
Maximum more number of combinations that he can try=24-2=22