99^2, 999^2, 9999^2............

992, 9992, 99992............ 


For numbers like 99, 999, 9999, use this trick:


(N2) = (N-1) ∣ 0.......01


Ex:



  • 992 = (99−1)∣01 = 9801

  • 9992 = (999−1)∣001 = 998001

  • 99992 = (9999−1)∣0001 = 99980001

  •  999992 = (99999−1)∣00001 = 9999800001