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发表于 10-2-2011 09:43:55|来自:新加坡
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小二数学家长辅导手记 (11)偶数与奇数 (even number&odd number)
When Pedro counts his pennies, he likes to make two piles that are the same height.
He has an EVEN number if he can make the piles the same height. If he can't, he has an ODD number of pennies.
Write "even" or "odd" beside each group of pennies using Pedro's method. Make piles of real pennies if it will help you.
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Number of Pennies Even or Odd
6
9
14
16
22
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上面是来自美国网站的一个关于偶/奇数的练习题,可以比较好地体会偶/奇数概念:能均等地分成两整份的是偶数(even number),不能的是奇数 (odd number)。
even number: 0, 2, 4, 6,8 ... (0=0+0; 2=1+1; 4=2+2; 6=3+3; 8=4+4)
odd number: 1, 3, 5, 7, 9 ...
Color the following numbers that are even:
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39
40 41 42 43 44 45 46 47 48 49
50 51 52 53 54 55 56 57 58 59
60 61 62 63 64 65 66 67 68 69
70 71 72 73 74 75 76 77 78 79
80 81 82 83 84 85 86 87 88 89
90 91 92 93 94 95 96 97 98 99
个位是 0,2,4,6,8的是偶数, 1,3,5,7,9的是奇数。(为什么?)
练习:Are the following numbers are even or odd?
5, 22, 33, 78, 234, 34567, 1234567890
来自网上的一道趣味题:
天色已晚,妈妈叫小明打开房间电灯,可淘气的小明一连拉了9下开关。请你说说这时灯是亮还是不亮?拉20下呢?拉100下呢?
我编了一个:
假如你们班男女同学各有15名,排成一队,依次是男同学女同学男同学女同学....。请问,第10位是男同学还是女同学?第15位呢?最后一位呢? |
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