UPSC Civil Services 2017 Prelims General Studies Paper II

Number of digits used For 1 – 9 = 9 × 1 = 9
Number of digits used For 10 – 99 = 90 × 2 = 180
Number of digits used for 100 – 150 = 51 × 3 = 153
Hence, 153 + 180 + 9 = 342 digits.