12+14+16+18+2+4+6+8
=12+8+14+6+18+2+16+5
=20+20+20+20
=80
200x2+200x2
=400+400=800
12+14+16+18+2+4+6+8
=(12+8)+(14+6)+(16+4)+(18+2)
=20+20+20+20
=80
200x2+200x2
=(200+200)X2
=800
=2
12+14+16+18+2+4+6+8
=12+8+14+6+18+2+16+5
=20+20+20+20
=80
200x2+200x2
=400+400=800
12+14+16+18+2+4+6+8
=(12+8)+(14+6)+(16+4)+(18+2)
=20+20+20+20
=80
200x2+200x2
=(200+200)X2
=800
=2
Tinh nhanh: 2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19=?
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20=
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20=
Số?
4:2=… 8:2=…
14:2=… 12:2=…
6:2=… 18:2=…
16:2=… 12:2=…
20-18+16-14+12-10+8-6+4-2 tính nhanh
Tính nhẩm:
4 : 2 = ..... 8 : 2 = .....
14 : 2 = ..... 18 : 2 = .....
6 : 2 = ..... 10 : 2 = .....
16 : 2 = ..... 20 : 2 = .....
Đố mọi người : 1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20 = ?
tình nhanh
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19