When creating the number of three digits by choosing and putting three sheets in order out of four cards, 1, 2, 4, and 7, how many kinds of multiples of 2 are made?
Answer
Thus, since the number of ones digit is two kinds, hundreds digit is three kinds except one sheet used at ones digit and tens digit can consider two kinds except two sheets used at both of ones digit and hundreds digit, and it is in all 2 × 3 × 2 = 12 kinds.
12 kinds
Solution
Since it comes to be a multiple of 2, ones digit is set to 2 or 4. Thus, since the number of ones digit is two kinds, hundreds digit is three kinds except one sheet used at ones digit and tens digit can consider two kinds except two sheets used at both of ones digit and hundreds digit, and it is in all 2 × 3 × 2 = 12 kinds.
