\(1+2+3+4+5+6+7+8+9+10\)\(10=55\)
\(10+20+30+40+50+60+70+80\)\(+90+100=550\)
K mình nhahải anh
Chúc bạn học giỏi
a) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5 + 10
= 10 x 4 + 15
= 40 + 15
= 55
b) 10 + 20 + 30 + 40 + 50 + 60 + 70 + 80 + 90 + 100
= ( 10 + 90 ) + ( 20 + 80 ) + ( 30 + 70 ) + ( 40 + 60 ) + 50 + 100
= 100 x 4 + 150
= 400 + 150
= 550
a)
(1+9)+(2+8)+(3+7)+(4+6)+5+10
=10+10+10+10+10+5
= 50 + 5
=55
b)
(10+90)+(20+80)+(30+70)+(40+60)+100+50
=100+100+100+100+100+50
=500+50
=550
a) 1+ 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5 + 10
= 10 + 10 + 10 + 10 + 5 + 10
= 10 x 5 + 5
= 50 +5 = 55
b) 10 + 20 + 30 + 40 + 50 + 60 + 70 + 80 +90 + 100
= ( 10 + 90 ) + ( 20 + 80 ) + ( 30 + 70 ) + ( 40 + 60 ) + 50 + 100
= 100 + 100 + 100 + 100 + 50 + 100
= 100 x 5 + 50
= 500 + 50 = 550
Các bạn tk cho mình nha.
hải anh |
Tính nhanh
a) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 10 + 5
= 10 + 10 + 10 + 10 + 10 + 5
= 55
b) 10 + 20 + 30 + 40 + 50 + 60 + 70 + 80 + 90 + 100
= ( 10 + 90 ) + ( 20 + 80 ) + ( 30 + 70 ) + ( 40 + 60 ) + 100 + 50
= 100 + 100 + 100 + 100 + 100 + 50
= 550
a) 1+2+3+4+5+6+7+8+9+10
=(1+9)+(2+8)+(3+7)+(4+6)+5+10
=10x4+15
=40+15
=55
b)10+20+30+40+50+60+70+80+90+100
=(10+90)+(20+80)+(30+70)+(40+60)+50+100
=100x4+150
=400+150
=550
A=1+2+3+4+5+6+7+8+9+10
A=10+9+8+7+6+5+4+3+2+1
2A=11+11+...+11+11(có 10 số hạng 11)
A=11*10/2
A=55
B=10+20+30+40+50+60+70+80+90+100
B=100+90+80+70+60+50+40+30+20+10
2B=110+110+...+110+110(có 11 số hạng 110)
B=110*10/2
B=550
a) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= ( 1 +10 ) + ( 2 + 9 ) + ( 3 + 8 ) + ( 4 + 7 ) + ( 5 + 6 )
= 11 + 11 + 11 + 11 + 11
= 11 x 5
= 55
a) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5 + 10
= 10 + 10 + 10 + 10 + 5 + 10
= 55
b) 10 + 20 + 30 + 40 + 50 + 60 + 70 + 80 + 90 +100
= ( 10 + 90 ) + ( 20 + 80 ) + ( 30 + 70 ) + ( 40 + 60 ) + 50 + 100
= 100 + 100 + 100 + 100 + 50 + 100
= 550