SHA-256("120-bit")=7914af6a8fe938aacca6c2e60ae391bc7da6ecd858d33169be8ea60f42ec9078
mask120=0000000000000000000000000000000000ffffffffffffffffffffffffffffff
samplePrivKey120=0000000000000000000000000000000000a6ecd858d33169be8ea60f42ec9078
mask80=00000000000000000000000000000000000000000000ffffffffffffffffffff
samplePrivKey80=000000000000000000000000000000000000000000003169be8ea60f42ec9078
subtractionMask40=0000000000000000000000000000000000ffffffffff00000000000000000000
subtractPrivKey40=0000000000000000000000000000000000a6ecd858d300000000000000000000
Then you substract from 120 -(80+40) you get around119.9 !!!