巧用凑十法口算

巧用凑十法速算,二年一班,（一）以不变应万变,9+0=56+0=98+0=100+0=,110=420=730=940=,任何数加0、减0都还得任何数,10,5=,10,5=,90=180=870=1000=,任何数乘0都得0,10,5=,10,5=,19=181=861=1001=,任何数乘1还得任何数,（二）凑十歌,一九一九好朋友，,二八二八手拉手，,三七三七真亲密，,四六四六一起走，,五五凑成一双手。,9+1=1+9=8+2=2+8=7+3=3+7=6+4=4+6=5+5=,一看：二分：三凑：四连加：,看大数,分小数,大数凑十,把所有的数加起来,（三）运用凑十法速算,9+7=,9+8=,8+5=,8+2+3=,7+6=,7+3+3=,6+5=,6+4+1=,9+1+6=,16,17,13,13,11,9+1+7=,8+7=7+5=9+6=6+6=,（四）添数凑整算加法,19+（）=2028+（）=3037+（）=4056+（）=6069+（）=7078+（）=80,19+5=,19+1+4=,24,26+5=28+4=57+6=18+7=89+6=,26+4+1=,62,28+2+2,=72,57+3+3,=75,18+2+5,=71,89+1+5,=90,59+6=78+9=67+6=29+3=88+6=,65,87,73,32,94,19=28=37=56=,20-（）,30-（）,40-（）,60-（）,（五）灵活运用凑整算加法,54+19=,54+20,=73,-1,35+27=23+49=57+18=42+29=74+16=,35+30-3=,62,23+50-1,=72,57+20-2,=75,42+30-1,=71,74+20-4,=90,45+17=56+28=52+39=47+39=63+27=,45+20-3=,56+30-2=,52+40-1=,47+40-1=,63+30-3=,62,84,91,86,90,14+18=25+27=56+39=75+18=25+29=,14+20-2=,32,25+30-3,=52,56+40-1,=95,75+20-2,=93,25+30-1,=54,35-9=,35-10,=26,+1,(六)添数凑十算减法,43-8=76-7=54-6=,43-10+2=,35,76-10+3=,69,54-10+4=,48,31-9=62-8=74-7=53-6=68-9=,31-10+1=,22,62-10+2=,54,74-10+3=,67,53-10+4=,68-10+1=,47,59,37-9=67-8=71-7=52-6=65-9=,37-10+1=,28,67-10+2=,59,71-10+3=,74,52-10+4=,65-10+1=,46,56,65-29=,65-30,=36,+1,七、举一反三,32-19=63-48=75-27=54-39=85-59=,32-20+1=,13,63-50+2=,15,75-30+3=,48,54-40+1=,15,85-60+1=,16,43-26=56-38=65-47=54-29=85-59=,43-30+4=,