How can the six character daimoku (Nam Myo Ho Ren Ge Kyo) equal the seven character daimoku (Na mu Myo Ho Ren Ge Kyo)?

"Now I, Nichiren, have inherited the seven characters Nam-myoho-renge-kyo within the treasure tower and in this era of the Latter Day of the Law I work to disseminate them throughout Japan." -- SGI/NST dishonest translation.

"Now I, Nichiren, have inherited the seven characters Namu-myoho-renge-kyo within the treasure tower and in this era of the Latter Day of the Law I work to disseminate them throughout Japan." --  accurate translation