小学数学二年级第七单元两位数加减两位数口算ppt课件维语.ppt

,26+30=,56,48+20=,68,59-10=,49,66+3=,69,28-9=,19, , ., 2- . . ,2(4)39,2(3) 32,68 ., .,2(2)31,2(1)23, ., , ,68 .,1. , 68 .,2(1)- 2(2)-2(3)- 2(4)-,1. ( ),2(1)- 2(3)-2(2)- 2(4)-2(1)- 2(4)-2(2)- 2(3)-,23+31=32+39=,23+32=31+39=,23+39=32+31=,23 + 31 =,30,1,54,20,3,53,54,23 + 31 =,54,51,54,54,23 + 31 =,20,3,34,54,54,23 + 31 =,30,1,24,54,54,54,3,30,1,50,4,54,23 + 31 =,20,54, , - .,32+39=,.,23+31=5432+39=71,23+32=5531+39=70,23+39=6232+31=63,1- ,2- ：,3- ：, ,( ),( ),2(2)- 31,2(3)- 32,2(1)- 21,2(4)- 39,2(3)- , ,1. ,68-54=,14（）,60-50=10,8-4=4,10+4=14,68-50=18,18-4=14,2. ,32-14=, ., 28 65 ., ., ,23,35,27,56,56,47,+65,-24,+36,-26,+18,-37,88,32,83,9,45,19,94-52= 2 80-66= 4 34+53= 7 47+38= 5 74-58= 6 45+29= 4,4,1,8,8,1,7, : :, ,72,58 ,25 ,37 , ,36, 。,25,53,53,36,38,26,28,26,22,75,25,75,21,89,39+29,17+58,33+4,51+24,27+54,36+32,68,75,81, .,2,8, .,23,45,54,23+22,58-35,90-45,31+23,87-64,18,15,25,1. 2. ,46, ,46+25=71（）,18+15+25=58(), ,