1) 23 * 4 = (20 + 3) * 4 = 20 * 4 + 3 * 4 = 80 + 12 = 92
2) 236 * 8 = (200 + 30 + 6) * 8 = 200 * 8 + 30 * 8 + 6 * 8 = 1600 + 240 + 48 = 1888