先估一估,再用竖式计算.38×42=积大约是 先估一估大约是多少,再列竖式算一算.452×63
\u5148\u25a1\u5934\u4f30\u4e00\u4f30\u79ef\u5927\u7ea6\u662f\u591a\u5c11\uff0c\u518d\u5217\u7ad6\u5f0f\u8ba1\u7b97\uff0e278\u00d738 52\u00d7404 201\u00d727 &nb...\uff081\uff09278\u00d738\u2248280\u00d740=11200\uff1b278\u00d738=10564\uff1b\uff082\uff0952\u00d7404\u224850\u00d7400=20000\uff1b52\u00d7404=21008\uff1b\uff083\uff09201\u00d727\u2248200\u00d727=5400\uff1b201\u00d727=5427\uff1b\uff084\uff0963\u00d719\u224860\u00d720=1200\uff1b63\u00d719=1197\uff0e
\u4f30\u7b97\u4e00\u4e0b\uff1a450\u00d760=27000
452\u00d763 = 28476\u5217\u7ad6\u5f0f
积大约是1600
63×29=1827
积大约是 1800
52×60=3120
积大约是3000
故答案为:1600;1800;3000.
绛旓細浼颁竴浼板啀鍒绔栧紡璁$畻364x8 364脳8=2912 鏈夌敤璇烽噰绾炽
绛旓細鍏堜及涓浼板啀鐢ㄧ珫寮忚绠36X7 璁$畻锛 36脳7=252
绛旓細36x7鈮40脳7=280 48x6鈮50脳6=300绔栧紡濡備笅锛
绛旓細45*7 =(40+5)*7 =40*7+5*7 =280+35 =315 45 脳 7 = 315
绛旓細鐢ㄧ珫寮忚绠銆(鍏堜及涓浼,鍐嶇畻涓绠)46X24 46脳24=1104
绛旓細瀵瑰悧锛
绛旓細鍏堜及涓浼板啀鍒绔栧紡璁$畻31x23 1銆佷及绠楋細31x23 鈮30x20 =600 2銆佸垪绔栧紡璁$畻锛31x23=713
绛旓細鐪嬪浘鐗
绛旓細鍏堜及涓浼鍦ㄥ垪绔栧紡璁$畻146x7 146脳7鈮150脳7=1050 146脳7=1022
绛旓細鍏堜及涓浼板啀鐢ㄧ珫寮忚绠720脳9绛変簬澶氬皯 璁$畻锛 720脳9=6480