English
If the remainder r is zero, then the current quotient q equals the previous quotient qp plus one.
Русский
Если остаток r равен нулю, то q = qp + 1.
LaTeX
$$$(hr : u.r = 0) \\Rightarrow u.q = u.qp + 1$$$
Lean4
theorem qp_eq (hr : u.r = 0) : u.q = u.qp + 1 := by
by_cases hq : u.q = 0
· let h := u.rq_eq
rw [hr, hq, mul_zero, add_zero] at h
cases h
· exact (Nat.succ_pred_eq_of_pos (Nat.pos_of_ne_zero hq)).symm