tính bằng cách hợp lý( tính nhanh):
a) 53:52+96.
b) 21*16+37*31+21*63
c) 35*48+65*68+20*35
d)711:79-62+23*2
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 * 100 bằng bao nhiêu?
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+56+57+58+59+60+61+62+63+64+65+66+67+68+69+70=?
Bài 2: Tính hợp lí
a.1152-(374+1152)+(-65+374)
b.[53+(-76)]-[-76-(-53)]
c.-48+48.(-78)+21.(-48)
d.(-12).47(-12).52+(-12)
e.(-1)+(-3)+...(-199)+(-201)
f.17+(-20)+23+(-26)+...+53+(-56)
Mấy bạn giúp mình
tính nhanh
a, 53 . 84 + 212 . 29
b, 79 . 17 + 21 . 18
c, 16 + 21 + 26 + 31 + ... + 96 + 101
tính nhanh
a, 53 . 84 + 212 . 29
= 4452 + 6148
= 10600
b, 79 . 17 + 21 . 18
= 1343 + 378
= 1721
c, 16 + 21 + 26 + 31 + ... + 96 + 101
= ( 101 + 16 ) x 18 2
= 1053
Tính hợp lý:
a) 52 - 42 + 37 - 28 + 38 + 63 b) 130 + 35.19 - 9.70 - 30
c) (11 + 13 + 15 + ... + 19).(6.8 - 48) d) (72 - 8.9):(20 + 22 + 24 - 19 + 21 + 23)
Tính hợp lý:
a, 52 – 42 + 37 – 28 + 38 + 63
b, 130 + 35.19 – 9.70 – 30
c, (11 + 13 + 15 + … + 19).(6.8 – 48)
d, (72 – 8.9):(20+22+24 – 19 +21+23)
a) 52 – 42 + 37 – 28 + 38 + 63 = (52 – 42) + (37 + 63) + (38 – 28) = 10 + 100 + 10 = 120
b) 130 + 35.19 – 9.70 – 30
= (35.19 – 9.70) + (130 – 30) = (35.19 – 9.35.2) + 100 = 35.(19 – 18) + 100 = 35 + 100 = 135
c) (11 + 13 + 15 + … + 19).(6.8 – 48) = (11+13+15+…+19).0 = 0
d) (72 – 8.9):(20+22+24 – 19 +21+23) = 0:(20+22+24 – 19 +21+23) = 0
số 1 : tính nhanh
A = 78 x 31 + 78 x 24 + 78 x 17 + 22 x 72
C = 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
B = 35 x 34 + 35 x 86 + 65 x 75 + 65 x 45
D = 27 x 332 + 68 x 27 + 73 x 332 + 68 x 73
E = 2 x 53 x 12 + 4 x 6 x 37 + 2 x 38 x 12
F = 3 x25 x 8 + 4 x 6 x 37 + 2 x 38 x 12
A = 78 x 31 + 78 x 24 + 78 x 17 + 22 x 72
A = 78 x ( 31 + 24 + 17 ) + 22 x 72
A = 78 x 72 + 22 x 72
A = 72 x ( 78 + 22 )
A = 72 x 100
A = 7200
C = 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
C = 39 x ( 53 + 47 ) - 21 x ( 53 - 47 )
C = 39 x 100 - 21 x 6
C = 3900 - 126
C = 3774
A = 78 x 31 + 78 x 24 + 78 x 17 + 22 x 72
A = 78 x ( 31 + 24 +17 ) + 22 x 72
A = 78 x 72 + 22 x 72
A = 72 x ( 78 + 22 )
A = 72 x 100
A = 7200
số 1 tính nhanh A 78 x 31 78 x 24 78 x 17 22 x 72C 53 x 39 47 x 39 53 x 21 47 x 21B 35 x 34 35 x 86 65 x 75 65 x 45D 27 x 332 68 x 27 73 x 332 68 x 73E 2 x 53 x 12 4 x 6 x 37 2 x 38 x 12F 3 x25 x 8 4 x 6 x 37 2 x 38 x 12