(1+2+3+4+5)乘6-7+8+9
123-45-67+89=1001X23X4-56/7/8+9=1001+23X4+5-6+7-8+9=1001+23X4-5+6+7+8-9=100 1-2-3+4X5X6+7+8+9=100