* 5+1= 6 1+5= 6 5+1= 1+5= 6 6 4+2= 2+4= 6 6 3+3= 6 6+1= 1+6= 7 7 5+2= 2+5= 7 7 4+3= 3+4= 7 7 6-1= 6-5= 5 1 6-2= 6-4= 4 2 6-3= 3 7-1= 7-6= 6 1 7-2= 7-5= 5 2 7-3= 7-4= 4 3 7-2= 5 7-5= 2 5+2= 7 2+5= 7 4+2= 6 2+4= 6 6 4 + 2 = 2 + = 6 - 2 = 6 - = 4 6 4 4 2 *
6和7的加减法.ppt
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