| i % 10 = 0 ∧ j ≠ 0, ∀ i1, i2, j, j0. i→n(i1) + i→n(i2) < i→n(i) + i→n(i0) → true → mkDecimal(i1, j) * mkDecimal(i2, j0) = mkDecimal(i1 * i2, abs(j) + abs(j0)) ⊦ mkDecimal(i / 10, abs(j) - 1) * mkDecimal(i0, j0) = mkDecimal(i * i0, abs(j) + abs(j0)) |
i % 10 = 0, ∀ i1, i2, j, j0. i→n(i1) + i→n(i2) < i→n(i) + i→n(i0) → true → mkDecimal(i1, j) * mkDecimal(i2, j0) = mkDecimal(i1 * i2, abs(j) + abs(j0)) ⊦ j = 0, mkDecimal(i / 10, abs(j) - 1) * mkDecimal(i0, j0) = mkDecimal(i * i0, abs(j) + abs(j0))