Question

Bài 1.2: Tính nhanh:

5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5

25 + 25 + 25 + 25 + 25 + 25 +25 + 25

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15

2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18

125 + 125 + 125 + 125 - 25 - 25 - 25 - 25

Answer 1

5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5=5x10=50

Answer 2

25 + 25 + 25 + 25 + 25 + 25 +25 + 25=25x8=200

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15=(45x4)+(15x4)=180+60=240

Answer 3

5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5
= 5 x 10
= 50

25 + 25 + 25 + 25 + 25 + 25 +25 + 25
= 25 x 8
= 200

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15
= 45 x 4 + 15 x 4
= 180 + 60
= 240

2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18
= (2 + 18) + (4 + 16) + (8 + 12) + (6 + 14) + 10
= 20 + 20 + 20 + 20 + 10 
= 20 x 4 + 10
= 80 + 10
= 90 

125 + 125 + 125 + 125 - 25 - 25 - 25 - 25 
= 4 x (125 - 25) 
= 4 x 100 
= 400
(Tick cho mk pls ^^)

Answer 4

5 + 5 + 5 + 5 + 5 + 5 + 5 + 5 + 5 + 5 = 5 x 10 = 50

25 + 25 + 25 + 25 + 25 + 25 + 25 + 25  = 25 x 8 = 200

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15 = 45 x 4 + 15 x 4 = 180 + 60 = 240

2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 = ( 2 + 18 ) + ( 4 + 16 ) + ( 6 + 14 ) + ( 8 + 12 ) + 10 = 20 + 20 + 20 + 20 + 10 = 20 x 4 + 10 = 90

125 + 125 + 125 + 125 - 25 - 25 - 25 - 25 = 125 x 4 - 25 x 4 = 500 - 100 = 400

k đúng cho mình nhé !!! Mình cảm ơn !!!

Answer 5

50

200

240

90

Answer 6

 

 

5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5=5x10=50

25 + 25 + 25 + 25 + 25 + 25 +25 + 25=25x8=200

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15=45x4+15x4=180+60=240

2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18=(18+2)+(16+4)+(14+6)+(12+8)+10=20+20+20+20+10=20x5+10=10110

125 + 125 + 125 + 125 - 25 - 25 - 25 - 25=125x4-25x4=500-100=400