Question

A device can write 100 digits in 1 minutes.it starts writing natural numbers. the device is stopped after running it for half an hour. it is found that the last number it was writing is incomplete. the number is.

Answer 1

natural number start with 1
in half hour hour he write 50 digits
1 to 9 their are 9 digits
from 10 their are 2 digits in one number
40 digits are from 10 to 29
left one is 3 of 30
the no. which left to complete is 30

Answer 2

The  last number which was writing  incomplete  is 1027.

Step-by-step explanation:

Given:

100 digits in 1 minutes can be written by a device.

The device writes natural numbers.

The device is stopped after running it for half an hour.

To Find:

The  last number which was writing  incomplete.

Solution:

Total number  of digits after running it for half an hour  $= 100\times30=3000$

Total  number of digits used till number 999 $=9+90\times2+900\times3=2889.$

For remaining 111 digits and now numbers are  of 4 digits,

Therefore, $\frac{111}{4} =27+\frac{3}{4}$

Hence last number is $999+27= 1026 +1=1027 th\ number.$

Thus,the  last number which was writing  incomplete  is 1027.

PROJECT CODE#SPJ3