如67*47=3149,后两位数字49由7*7得来,前两位数字31由6*4+7得到,请再写几个这样的算式。急快一点
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对个位相同,十位上的数字和为10的两个数相乘,总有
乘积的末两位等于个位的平方,乘积的高位等于十位数相乘的积与个位的和。
即对两位数MB、NB,M+N=10,有
(10M + B )* (10N + B )
= 100*M*N + 10*B*N + 10*B*M + B²
= 100*M*N + 100B + B²
= 100(M*N + B) + B²
根据这个规律,有如下式子:
11*91 = 10 01 :1*9+1 = 10,1*1 = 01
12*92 = 11 04 :1*9+2 = 11,2*2 = 04
13*93 = 12 09 :1*9+3 = 12,3*3 = 09
14*94 = 13 16 :1*9+4 = 13,4*4 = 16
15*95 = 14 25 :1*9+5 = 14,5*5 = 25
16*96 = 15 36 :1*9+6 = 15,6*6 = 36
17*97 = 16 49 :1*9+7 = 16,7*7 = 49
18*98 = 17 64 :1*9+8 = 17,8*8 = 64
19*99 = 18 81 :1*9+9 = 18,9*9 = 81
21*81 = 17 01 :2*8+1 = 17,1*1 = 01
22*82 = 18 04 :2*8+2 = 18,2*2 = 04
23*83 = 19 09 :2*8+3 = 19,3*3 = 09
24*84 = 20 16 :2*8+4 = 20,4*4 = 16
25*85 = 21 25 :2*8+5 = 21,5*5 = 25
26*86 = 22 36 :2*8+6 = 22,6*6 = 36
27*87 = 23 49 :2*8+7 = 23,7*7 = 49
28*88 = 24 64 :2*8+8 = 24,8*8 = 64
29*89 = 25 81 :2*8+9 = 25,9*9 = 81
31*71 = 22 01 :3*7+1 = 22,1*1 = 01
32*72 = 23 04 :3*7+2 = 23,2*2 = 04
33*73 = 24 09 :3*7+3 = 24,3*3 = 09
34*74 = 25 16 :3*7+4 = 25,4*4 = 16
35*75 = 26 25 :3*7+5 = 26,5*5 = 25
36*76 = 27 36 :3*7+6 = 27,6*6 = 36
37*77 = 28 49 :3*7+7 = 28,7*7 = 49
38*78 = 29 64 :3*7+8 = 29,8*8 = 64
39*79 = 30 81 :3*7+9 = 30,9*9 = 81
41*61 = 25 01 :4*6+1 = 25,1*1 = 01
42*62 = 26 04 :4*6+2 = 26,2*2 = 04
43*63 = 27 09 :4*6+3 = 27,3*3 = 09
44*64 = 28 16 :4*6+4 = 28,4*4 = 16
45*65 = 29 25 :4*6+5 = 29,5*5 = 25
46*66 = 30 36 :4*6+6 = 30,6*6 = 36
47*67 = 31 49 :4*6+7 = 31,7*7 = 49
48*68 = 32 64 :4*6+8 = 32,8*8 = 64
49*69 = 33 81 :4*6+9 = 33,9*9 = 81
51*51 = 26 01 :5*5+1 = 26,1*1 = 01
52*52 = 27 04 :5*5+2 = 27,2*2 = 04
53*53 = 28 09 :5*5+3 = 28,3*3 = 09
54*54 = 29 16 :5*5+4 = 29,4*4 = 16
55*55 = 30 25 :5*5+5 = 30,5*5 = 25
56*56 = 31 36 :5*5+6 = 31,6*6 = 36
57*57 = 32 49 :5*5+7 = 32,7*7 = 49
58*58 = 33 64 :5*5+8 = 33,8*8 = 64
59*59 = 34 81 :5*5+9 = 34,9*9 = 81
乘积的末两位等于个位的平方,乘积的高位等于十位数相乘的积与个位的和。
即对两位数MB、NB,M+N=10,有
(10M + B )* (10N + B )
= 100*M*N + 10*B*N + 10*B*M + B²
= 100*M*N + 100B + B²
= 100(M*N + B) + B²
根据这个规律,有如下式子:
11*91 = 10 01 :1*9+1 = 10,1*1 = 01
12*92 = 11 04 :1*9+2 = 11,2*2 = 04
13*93 = 12 09 :1*9+3 = 12,3*3 = 09
14*94 = 13 16 :1*9+4 = 13,4*4 = 16
15*95 = 14 25 :1*9+5 = 14,5*5 = 25
16*96 = 15 36 :1*9+6 = 15,6*6 = 36
17*97 = 16 49 :1*9+7 = 16,7*7 = 49
18*98 = 17 64 :1*9+8 = 17,8*8 = 64
19*99 = 18 81 :1*9+9 = 18,9*9 = 81
21*81 = 17 01 :2*8+1 = 17,1*1 = 01
22*82 = 18 04 :2*8+2 = 18,2*2 = 04
23*83 = 19 09 :2*8+3 = 19,3*3 = 09
24*84 = 20 16 :2*8+4 = 20,4*4 = 16
25*85 = 21 25 :2*8+5 = 21,5*5 = 25
26*86 = 22 36 :2*8+6 = 22,6*6 = 36
27*87 = 23 49 :2*8+7 = 23,7*7 = 49
28*88 = 24 64 :2*8+8 = 24,8*8 = 64
29*89 = 25 81 :2*8+9 = 25,9*9 = 81
31*71 = 22 01 :3*7+1 = 22,1*1 = 01
32*72 = 23 04 :3*7+2 = 23,2*2 = 04
33*73 = 24 09 :3*7+3 = 24,3*3 = 09
34*74 = 25 16 :3*7+4 = 25,4*4 = 16
35*75 = 26 25 :3*7+5 = 26,5*5 = 25
36*76 = 27 36 :3*7+6 = 27,6*6 = 36
37*77 = 28 49 :3*7+7 = 28,7*7 = 49
38*78 = 29 64 :3*7+8 = 29,8*8 = 64
39*79 = 30 81 :3*7+9 = 30,9*9 = 81
41*61 = 25 01 :4*6+1 = 25,1*1 = 01
42*62 = 26 04 :4*6+2 = 26,2*2 = 04
43*63 = 27 09 :4*6+3 = 27,3*3 = 09
44*64 = 28 16 :4*6+4 = 28,4*4 = 16
45*65 = 29 25 :4*6+5 = 29,5*5 = 25
46*66 = 30 36 :4*6+6 = 30,6*6 = 36
47*67 = 31 49 :4*6+7 = 31,7*7 = 49
48*68 = 32 64 :4*6+8 = 32,8*8 = 64
49*69 = 33 81 :4*6+9 = 33,9*9 = 81
51*51 = 26 01 :5*5+1 = 26,1*1 = 01
52*52 = 27 04 :5*5+2 = 27,2*2 = 04
53*53 = 28 09 :5*5+3 = 28,3*3 = 09
54*54 = 29 16 :5*5+4 = 29,4*4 = 16
55*55 = 30 25 :5*5+5 = 30,5*5 = 25
56*56 = 31 36 :5*5+6 = 31,6*6 = 36
57*57 = 32 49 :5*5+7 = 32,7*7 = 49
58*58 = 33 64 :5*5+8 = 33,8*8 = 64
59*59 = 34 81 :5*5+9 = 34,9*9 = 81
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97*17=1649 后两位7*7=49,前两位9*1+7=16
87*27=2349 后两位7*7=49,前两位8*2+7=23
77*37=2849 后两位7*7=49,前两位7*3+7=28
57*57=3249 后两位7*7=49,前两位5*5+7=32
希望这个回答对你有帮助
87*27=2349 后两位7*7=49,前两位8*2+7=23
77*37=2849 后两位7*7=49,前两位7*3+7=28
57*57=3249 后两位7*7=49,前两位5*5+7=32
希望这个回答对你有帮助
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34*47 后两位数字28由4*7得来,前两位数字13由3*4+2得到
54*68 后两位数字32由4*8得来,前两位数字33由5*6+3得到
77*56 后两位数字42由7*6得来,前两位数字39由7*5+4得到
54*68 后两位数字32由4*8得来,前两位数字33由5*6+3得到
77*56 后两位数字42由7*6得来,前两位数字39由7*5+4得到
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24*84 = 20 16 :2*8+4 = 20,4*4 = 16
27*87 = 23 49 :2*8+7 = 23,7*7 = 49
25*85 = 21 25 :2*8+5 = 21,5*5 = 25
23*83 = 19 09 :2*8+3 = 19,3*3 = 09
26*86 = 22 36 :2*8+6 = 22,6*6 = 36
27*87 = 23 49 :2*8+7 = 23,7*7 = 49
25*85 = 21 25 :2*8+5 = 21,5*5 = 25
23*83 = 19 09 :2*8+3 = 19,3*3 = 09
26*86 = 22 36 :2*8+6 = 22,6*6 = 36
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