Q. If a home uses 250 units, what is total energy in Joules?
Answer: 9 × 108 Joules
Notes: 1 unit = 1 kWh = 3.6 × 106 Joules. For 250 units: 250 × 3.6 × 106 = 9 × 108 Joules. Common in electricity billing, 1 unit means 1 kWh.