Bài 1. Tính nhanh:
a) 23.56+56.77
b) 32.19+32
c) 35.34+35.86+65.75+65.45 ;
d)43.17+29.57+13.43+57 .
Bài 1. Tính nhanh: a) 23.56+56.77 b) 32.19+32 c) 35.34+35.86+65.75+65.45 ; d)43.17+29.57+13.43+57 .
By Nevaeh
By Nevaeh
Bài 1. Tính nhanh:
a) 23.56+56.77
b) 32.19+32
c) 35.34+35.86+65.75+65.45 ;
d)43.17+29.57+13.43+57 .
Đáp án:
a) 23 . 56 + 56 . 77
= 56 . (23 + 77)
= 56 . 100
= 5600
b) 32 . 19 + 32
= 32 . 19 + 32 . 1
= 32 . (19 + 1)
= 32 . 20
= 640
c) 35 . 34 + 35 . 86 + 65 . 75 + 65 . 45
= [35 . (34 + 86)] + [65 . (75 + 45)]
= (35 . 120) + (65 . 120)
= 35 . 120 + 65 . 120
= 120 . (35 + 65)
= 120 . 100
= 12000
d) 43 . 17 + 29 . 57 + 13 . 43 + 57
= 43 . 17 + 29 . 57 + 13 . 43 + 57 . 1
= [43 . (17 + 13)] + [57 . (29 + 1)]
= (43 . 30) + (57 . 30)
= 43 . 30 + 57 . 30
= 30 . (43 + 57)
= 30 . 100
= 3000
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a)23.56+56.77
=56.(23+77)
=56.100
=5600
b)32 x 19 + 32
=32 x (19+1)
= 640
c) 35 x 34 +35 x 86 + 65 x 75 + 65 x 45
= 35 x ( 34 + 86 ) + 65 x ( 75 + 45 )
=35 x 120 + 65 x 120
= 4200 + 7800
= 12000
d) 43 x 17 + 29 x 57 + 13 x 43 + 57
= 731 + 1653 + 559 + 57
= 2384 + 616
= 3000