3+6+12+24+48+96+192的简便计算
问题描述:
3+6+12+24+48+96+192的简便计算
答
3+6+12+24+48+96+192
=3*1+3*2+3*4+3*8+3*16+3*32+3*64
=3*(1+2+4+8+16+32+64)
=3*1(1-2^6)/(1-2)
=3*127
=381