You accidentally slide a glass of milk off a table that is 0.9 m tall. how long does it take the milk to hit the ground.

Fine, lets do a retry of this.

Δd = -0.9m

v₁ = 0

v₂ = ?

a = -9.8 m/s²

Δt = ?

We can use the following kinematic equation and solve for Δt.

                             Δd = v₁Δt + 0.5(a)(Δt)²

                             Δd = 0.5(a)(Δt)²

                           2Δd = a(Δt)²

                     √2Δd/a = Δt

√2(-0.9m)/(-9.8 m/s²) = Δt

0.428571428574048 = Δt

Therefore, it takes 0.4 seconds for the glass to hit the ground, or 0.43s as you said (even though I don't believe it follows significant digit rules)