3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19
= (3 + 19) + (5 + 17) + (7 + 15) + (9 + 13) + 11
= 22 + 22 + 22 + 22 + 11
= 22 x 4 + 11
= 88 + 11
= 99
3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19
= (3 + 19) + (5 + 17) + (7 + 15) + (9 + 13) + 11
= 22 + 22 + 22 + 22 + 11
= 22 x 4 + 11
= 88 + 11
= 99
tính nhanh 1+3-5+7-9+11-13+15-17+19+ .. + 2015=?
Tính nhanh:
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19
3. Tính nhanh:
a, (1+3+5+7+9) - (0+2+4+6+8)=.........................................................................................
b, (11+13+15+17+19) - (10+12+14+16+18)=......................................................
1 + 3 − 5 + 7 + 9 − 11 + 13 + 15 − 17 + 19 + 21 − 23 + · · · + 205 + 207 − 209=?
Càng nhanh càng tốt nhá !
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20= ?
Tính bằng cách thuận tiện nhất nha.
AI NHANH MK TÍCH
Tính nhanh
19+18+17+16+15+14+13+12+11+10+9+8+7+6+5+4+3+2+2=......?
x=1+3+5+7+9+11+13+15+17+19
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+.....+99999999999956214 (tính tỏng)
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20
ai nhanh mink tick cho