39 × 102 + 31 × 102 + 23 × 48 + 47 × 48 = (39+31) × 102 + (23+47)×48 = 70 ×102 + 70 × 48 = (102+48) × 70= 70 × 150 = 10500
39 × 102 + 31 × 102 + 23 × 48 + 47 × 48 = (39+31) × 102 + (23+47)×48 = 70 ×102 + 70 × 48 = (102+48) × 70= 70 × 150 = 10500