简便运算。25×39+2538×65-55×38
算一算。
比一比,看谁算得快又对。3+1= 2+3= 4+1=1+0= 5–2= 4–4=0+5= 1–0= 2+0=3+0= 4–2= 0+0=5–4= 5–3= 4–0=0–0= 5–1= 3–2=
口算。6-5= 5-1= 7-1=7-4= 3-3= 7-5=4-1= 6-3= 6-4=7-7= 7-2= 7-6=7-3= 6-3= 5-4=6-2= 7-2= 7-3=7-4= ( )-4=2 6-( )=2( )-3=4 6-( )=3 7-( )=3
口算。7-3= 6-3= 5-4= 7-2=7-2= 6-2= 7-2= 6-4= 7-4=6-4= 5-4= 7-5= 6-2= 7-7=7-4= 5-3= 6-5= 5-1=7-4= 3-3= 7-5= 7-( )=5 ( )-3=2( )-0=6 6-( )=1 ( )-6=1
口算。7-7= 6-3= 7-3= 5-4= 7-4=6-2= 7-2= 6-4= 6-2= 7-2=7-4= 5-4= 7-5= 4-2= 6-4= 5-3=( )-5=2 ( )-3=0 6-( )=23-( )=2 6-( )=4 ( )-1=67-( )=3 ( )-2=4 7-( )=5( )-6=1 ( )-3=4 6-( )=2