(Q). Find the first two non zero digit i.e. FTNZD in 100×101×102×………..till 100 terms.
Solution:-
=
So we have to find FTNZD in
first find FTNZD(199!) ⇒
∴ FTNZD(199!) = 12⁴⁷ × Uₜ(24×24×42×1)
= (2²×3)⁴⁷ × Uₜ(76×42)
= 2⁹⁴ × 3⁴⁷ × 92
= (2²⁰)⁴ × 2¹⁴ × (81)¹¹ ×27 ×92
= 76 × 84 × 81 × 27 × 92
= 36
Now to find FTNZD(99!)
∴ FTNZD(99!) = 12²² × Uₜ(24×24×6)
= (2²×3)²² × Uₜ(76×6)
= 2⁴⁴ × 3²² × 56
= (2²⁰)² × 2⁴ × (81)⁵ × 3² × 56
= 76 × 16 × 01 × 9 × 56
= 64
Now 199! has 47 trailing zeros & 99! has 22 trailing zeros
∴ will have 47 – 22 = 25 trailing zeros
So FTNZD of will be the division of FTNZD of 199! & FTNZD of 99!
∴FTNZD = =
From given options Uₜ(64×24) = 36
Hence Answer = 24 option (iii) is correct.