| (dec_i.int + dec_j.int) % 10 = 0, dec_i.int + dec_j.int * 10 ^ (dec_i.scale - dec_j.scale + 1) * 10 = 0, 0 < dec_j.scale, 1 < dec_i.scale, 0 ≤ dec_i.scale + dec_j.scale, 0 ≤ dec_i.scale, 0 < dec_i.scale, dec_j.scale < dec_i.scale ⊦ dec_j.scale = 0, dec_i.int % 10 = 0, dec_i.scale = dec_j.scale |
⊦ i + j = i0 ↔ i = i0 - j
(dec_i.int + dec_j.int) % 10 = 0, dec_i.int = 0 - dec_j.int * 10 ^ (dec_i.scale - dec_j.scale + 1) * 10, 0 < dec_j.scale, 1 < dec_i.scale, 0 ≤ dec_i.scale + dec_j.scale, 0 ≤ dec_i.scale, 0 < dec_i.scale, dec_j.scale < dec_i.scale ⊦ dec_j.scale = 0, dec_i.int % 10 = 0, dec_i.scale = dec_j.scale
Used terms: 0, dec_j.int * 10 ^ (dec_i.scale - dec_j.scale + 1) * 10, dec_i.int