0.39乘以2.9先计算再验算,1000乘以0.39竖式计算,3.7x200竖式计算,0.39x2.9竖式计算并验算,0.39x2.9简便脱式计算,0.58乘0.08验算,018x8.45竖式计算并验算,4.5x0.002竖式计算并验算,0.39x2.9计算并验算,0.39x29的验算怎么算,39　34用竖式计算并验算,0.39　192简便计算,乘法验算怎么算