Question

A computer scans the digits of the counting numbers. For example, if it scans 1 2 3 4 5 6 7 8 9 10 11 12 then it sacned 15 digits. The computer begins its task and scans the first 1788 digits. The last number scanned is?

Answer 1

632

Explanation:

1 digit for the first 9 numbers,
2 digits por the next 90 numbers,
3 digits for the next 900 numbers... and so on...

So: digits for 9: 9
digits for 99: 9 + 90 * 2 = 189
digits for 999: 189 + 900 * 3 = 2889

As it is bigger than our number of digits 1788:

`1788 - 189 = 1599`

`1599 / 3 = 533`

`533 + 99 = 632`

So;

#Dig 632 = Dig 99 + Dig 533 = 189 + 1599 = 1788 #