估算78÷4 32×58 289÷6 89×41.
10+3= 10+6= 9+10= 5+10= 7+10= 10+8=
10+2= 10+3= 10+5=3+10= 4+10= 6+10=
7-0= 6-1= 7-3=8-5= 4-2= 9-7=
5+0= 10-2= 5-2= 7-3= 6-4= 8-4=
10-6= 8-6= 8-5=8-3= 5-4= 5-1=