用简便算法计算19*39又55/57
问题描述:
用简便算法计算19*39又55/57
答
原式=((20-1)*(40-1))*55/(3*19)
=(800-20-40+1)/((4/3)-(7/19))
=741/((4/3)-(7/19))
=(741*4/3)-(741*7/19)
=247*4-39*7
=988-273=715