What is sum to the 100 terms of the series `9+99+999+…?`

The sum of the first 10 terms of the series 9+99+999 +….., is

The sum to n terms of the series 9 + 99 + 999 + ……. Is

The sum of the first 10 terms of the series 9+99+999+ . . . Is

.The sum to 'n' terms of the series 9 + 99 + 999 ... ... is ] , [ 1) (10 ( 10^ n − 1 ) − n) 2) (10/ 9 [ 10^ n − 1 ] + n) 3) (10/ 9 [ 10^ n − 1 ] − n) 4) (10/ 9 [ 10^ n − 1) ]

What is the sum of 100 terms of the series 1-2+3-4+5-6+…. ?

The sum of 100 terms of the series 1 +3 + 5 +7 + 9 +11 + 13 +15 + ….. is :