Question

After about 1,000 charges, smartphones batteries lose about one-fifth of their charging capacity. A brand new phone is currently at 78%. What would this phone's battery percentage show after 1,000 charging cycles? (round to the nearest whole number)

Answer 1

If the phone’s displayed percentage drops by one‑fifth (20%), multiply 78% by 0.80:

78% × 0.80 = 62.4% → rounded = 62%.

(If instead you meant the same stored energy after capacity loss, the display would read 78% ÷ 0.80 = 97.5% ≈ 98%.)