1、奇數(shù)和偶數(shù)的運算性質(zhì),因數(shù)與倍數(shù),2,快樂大轉(zhuǎn)盤 規(guī)則：一個同學(xué)轉(zhuǎn)，指針指著哪個數(shù)，就加上這個數(shù)的本身。如果和是奇數(shù)，會得到大獎；和是偶數(shù)，則沒有獎。,奇數(shù)奇數(shù) 偶數(shù)偶數(shù),想要研究偶數(shù)和奇數(shù)的運算規(guī)律，除了這兩種情況，你還能想到其他的情況嗎？,奇數(shù)奇數(shù) 偶數(shù)偶數(shù),奇數(shù)偶數(shù),說一說：為什么不研究“偶數(shù)奇數(shù)”？,分小組探究并說說用到的方法。,可以隨意找?guī)讉€奇數(shù)、偶數(shù)相加。,奇數(shù)：5,7,9,11,偶數(shù)：8,12,20,24,58=13,78=15,57=12,79=16,812=20,1224=36,舉例法,奇數(shù)：5,7,9,11,偶數(shù)：8,12,20,24,58=13,78=15,57=12,7

2、9=16,812=20,1224=36,奇數(shù)偶數(shù)=奇數(shù),奇數(shù)奇數(shù)=偶數(shù),偶數(shù)偶數(shù)=偶數(shù),奇數(shù)偶數(shù)=奇數(shù),奇數(shù)奇數(shù)=偶數(shù),偶數(shù)偶數(shù)=偶數(shù),圖示法,這個結(jié)論正確嗎？,可以再找一些大數(shù)試試。,319+534=853,533+319=852,534+320=854,奇數(shù)偶數(shù)=奇數(shù),奇數(shù)奇數(shù)=偶數(shù),偶數(shù)偶數(shù)=偶數(shù),想一想：如果是減法呢？,同樣找一些奇數(shù)和偶數(shù)相減。,118=3,97=2,2012=8,奇數(shù)偶數(shù)=奇數(shù),奇數(shù)奇數(shù)=偶數(shù),偶數(shù)偶數(shù)=偶數(shù),2011=9,偶數(shù)奇數(shù)=奇數(shù),奇數(shù)與偶數(shù)的積是奇數(shù)還是偶數(shù)？奇數(shù)與奇數(shù)的積是奇數(shù)還是偶數(shù)？偶數(shù)與偶數(shù)的積呢？,可以隨意找?guī)讉€奇數(shù)、偶數(shù)相乘。,奇數(shù)：5,7,9

3、,11,偶數(shù)：8,12,20,24,58=40,78=56,57=35,79=63,812=96,820=160,奇數(shù)偶數(shù)=偶數(shù),奇數(shù)奇數(shù)=奇數(shù),偶數(shù)偶數(shù)=偶數(shù),不計算，直接判斷結(jié)果是奇數(shù)還是偶數(shù)。,12+16 16-12 103-71 13+71 114+25 19-12 1113 314 148,奇數(shù),偶數(shù),偶數(shù),偶數(shù),偶數(shù),奇數(shù),奇數(shù),偶數(shù),偶數(shù),填空。,（1）偶數(shù)+偶數(shù)+偶數(shù)=（ ） 奇數(shù)+奇數(shù)+奇數(shù)=（ ） （2）奇數(shù)+偶數(shù)+奇數(shù)=（ ） 奇數(shù)-偶數(shù)-偶數(shù)=（ ）,偶數(shù),奇數(shù),偶數(shù),奇數(shù),+ = 偶數(shù),遠遠到面包房去買面包，一個甜甜圈2元，一個三明治10元，一個巧克力面包3元。如果遠遠買了一些甜甜圈和三明治，他付給售貨員50元，找回11元，找得對嗎？說明理由。,50元,偶數(shù),偶數(shù),偶數(shù),偶數(shù)偶數(shù)=偶數(shù),答：11是奇數(shù)，所以找得不對。,這節(jié)課你們都學(xué)會了哪些知識？,奇數(shù)偶數(shù)=偶數(shù),奇數(shù)奇數(shù)=奇數(shù),偶數(shù)偶數(shù)=偶數(shù),偶數(shù)偶數(shù)=偶數(shù),奇數(shù)偶數(shù)=奇數(shù),奇數(shù)奇數(shù)=偶數(shù),奇數(shù)和偶數(shù)的運算性質(zhì),同類為偶，異類為奇。,有偶為偶，無偶為奇