北师大小学数学四上《3.4 有趣的算式》(共22张PPT)

(共22张PPT)
沈阳市沈河区朝阳街第一小学
9
9
9
9
9
9
9
9
9
8
8
8
8
8
8
8
8
7
7
7
7
7
7
7
6
6
6
6
6
6
5
5
5
5
5
4
4
4
4
3
3
3
2
2
1
1 12
123
1234
12345
123456
1234567
12345678
123456789

x 8 x 8
x 8
x 8
x 8
x 8
x 8
x 8
x 8

+ 1 = + 2 =
+ 3 =
+ 4 =
+ 5 =
+ 6 =
+ 7 =
+ 8 =
+ 9 =

11 111 1111 11111 111111 1111111 11111111 111111111 1111111111
1 12
123
1234
12345
123456
1234567
12345678
123456789

x 9 x 9 x 9 x 9 x 9 x 9 x 9
x 9 x 9
+ 2 = + 3 =
+ 4 =
+ 5 =
+ 6 =
+ 7 =
+ 8 =
+ 9 =
+10 =

x 55 =
x 555 =
x 5555 =
x 55555 =
x 555555 =
x 5555555 =
x 55555555 =
1210 123210
12343210
1234543210 123456543210 12345676543210 1234567876543210
22
222
2222
22222
222222
2222222
22222222
88 888 8888 88888 888888 8888888 88888888 888888888
9 98 987 9876 98765 987654
9876543 98765432
x 9 x 9 x 9 x 9 x 9 x 9
x 9 x 9
+ 7 = + 6 = + 5 = + 4 = + 3 = + 2 =
+ 1 = + 0 =
88 888 8888 88888 888888 8888888 88888888 888888888
9 98 987 9876 98765 987654
9876543 98765432
x 9 x 9 x 9 x 9 x 9 x 9
x 9 x 9
+ 7 = + 6 = + 5 = + 4 = + 3 = + 2 =
+ 1 = + 0 =
1 x 1 = 1 11 x 11 = 121 111 x 111 = 12321 1111 x 1111 = 1234321 11111 x 11111 = 123454321 111111 x 111111 = 12345654321 1111111 x 1111111 = 1234567654321
11111111 x 11111111 = 123456787654321
1 1
1 1
1 2 1
1
1
2
1
1
2
1 1 1
1 1 1
1 1 1
1 2 3 2 1
1
1
1
3
1
1
1
3
1 1 1 1
1 1 1 1
1 1 1 1
1 1 1 1
1 2 3 4 3 2 1
1
1
1
1
4
1
1
1
1
4
……
乘数有几个1,积中间的数字就是几?
1 x 1 = 1 11 x 11 = 121 111 x 111 = 12321 1111 x 1111 = 1234321 11111 x 11111 = 123454321 111111 x 111111 = 12345654321 1111111 x 1111111 = 1234567654321
11111111 x 11111111 = 123456787654321
9999 9999 x 9999 9999 =
999 9999 8 000 0000 1
99 x 99
= 99 x (100－1)
= 9900－99
= 9801
9900－99
9900－99
0
9
1
0
9
1
●
999 x 999
= 999x (1000－1)
= 999000－999
= 998001
999000－999
999000－999
0
9
1
0
9
1
142857 x 1=
142857 x 2=
142857 x 3=
142857 x 4=
142857
285714
428571
571428
1
4
2
8
5
7
1
4
2
8
5
7
×1
×1
×2
×3
×4
×5
×6
1
4
2
8
5
7
×2
×1
×2
×3
×4
×5
×6
1
4
2
8
5
7
×3
×1
×2
×3
×4
×5
×6
1
4
2
8
5
7
×4
×1
×2
×3
×4
×5
×6
1
4
2
8
5
7
×5
×1
×2
×3
×4
×5
×6
1
4
2
8
5
7
×6
×1
×2
×3
×4
×5
×6
142
857
14
28
57
142857×142857=20408122449
20408
122449
＋ = 142857
142857 x 7=999999