估算89×51，可以把89看作.l1T){)V.C;R1p:L9V8S.{6z2m.n.`*@-j4|;i，把51看作:Z-_5A*n8K'g;[)m+f，结果大约是/J8n8G*r.L。.a6U(W'x/r7N3])S2N/\8J6N1w