Brent@GMATPrepNow wrote:sukhman wrote:How many times the digits of a computer keyboard will be required to be pressed in typing 1st 100 natural numbers ?
In other words, how many digits are in the integers from 1 to 100 inclusive.
1-digit numbers: from 1 to 9 inclusive
There are such 9 integers, and each has 1 digit, for a total of
9 digits
3-digit numbers: 100
There is 1 such integer with 3 digits, for a total of
3 digits
2-digit numbers: from 10 to 99 inclusive
There are 90 such integers, and each has 2 digits, for a total of
180 digits
TOTAL number of digits =
9 +
3 +
180 =
192
Cheers,
Brent
Exactly how I would answer it. However there are 2 accepted definitions of "natural number", (reference
https://mathworld.wolfram.com/NaturalNumber.html) the second of which includes zero - which means that an alternative solution would look at the integers 0 to 99, yielding a total of (192 - 1) = 191
I believe we are both correct: 191 or 192, both acceptable.
However, the question states "how many times
will be required" and as 192 exceeds necessity, then 191 should be the overall winner! In other words, 191 will be required for either methiod.
PS: This is based on your answer of 192 being correct.
