3,7,8,9只能用一次怎么算等于24

2个回答

  • 1:3 × (7 - 8 + 9)

    2:3 × ((7 - 8) + 9)

    3:3 × (7 - (8 - 9))

    4:3 × (7 + 9 - 8)

    5:3 × ((7 + 9) - 8)

    6:3 × (7 + (9 - 8))

    7:3 × (9 + 7 - 8)

    8:3 × ((9 + 7) - 8)

    9:3 × (9 + (7 - 8))

    10:3 × (9 - 8 + 7)

    11:3 × ((9 - 8) + 7)

    12:3 × (9 - (8 - 7))

    13:(7 - 8 + 9) × 3

    14:((7 - 8) + 9) × 3

    15:(7 - (8 - 9)) × 3

    16:(7 + 9 - 8) × 3

    17:((7 + 9) - 8) × 3

    18:(7 + (9 - 8)) × 3

    19:(9 + 7 - 8) × 3

    20:((9 + 7) - 8) × 3

    21:(9 + (7 - 8)) × 3

    22:(9 - 8 + 7) × 3

    23:((9 - 8) + 7) × 3

    24:(9 - (8 - 7)) × 3