1 + 15 + 19 + 15
= (1 + 19) + ( 15 + 15)
= 20 + 30
= 50
\(1+15+19+15\)
\(=\left(1+19\right)+\left(15+15\right)\)
\(=20+30\)
\(=50\)
1 +15 +19 +15 = (1+19 ) +(15 +15 )
=20 +30 = 50
1+15+19+15=1+(10+5)+(10+9)+(10+5)
=1+10+5+10+9+10+5
=(1+9)+10+10+(5+5)
=10+10+10+10
=4*10=40
1+15+19+15=50
k mk nha
cảm ơn nhiều lắm nek
^^
muốn tính nhanh hon bạn lấy 15+15=30 rồi 30+1=31+19 thì 1+9 bang 10, 3+2(nho1)=50
1 + 15 + 19 + 15
= [ 1 + 19 ] + [ 15 + 15 ]
= 20 + 30
=50