d)1864312123=1 x 1 000 000 000 +8x100000000+6x10000000+4x1000000+3x100000+1x10000+2x1000+1x 100+2x10+3x1
e)3809=3x1000+8x100+0x0+9x1
f)280000923=2x100000000+8x10000000+0x0+0x0+0x0+0x0+9x100+2x10+3x1
Sper că te-am ajutat!