Please help with this math question..?

Question

The pages in a book are numbered starting with 1. The book has 250 pages. How many digits did the printer use in numbering the pages of the book?

a) 640
b) 642
c) 320
d) 321

Answer 1

If they all had 3 digits, you would have 750 digits (250 pages x 3 digits each).

But 99 of the pages (1-99) have two digits or less, so subtract 99.

750 - 99 = 651.

And 9 of the pages (1-9) have only one digit, so subtract another 9:

651 - 9 = 642.

There are multiple ways to get the answer, but I like the subtraction method the best.

Answer 2

There are 250 total pages. Since the first 99 only have two digits, only 151 have 3 which means 151*3=453 digits so far.

Of the remaining 99, only 90 have two digits (90*2=180)

The last 9 have 1 digit each: 9*1=9

Add the three answers:9+180+453=642

b is the correct answer

Answer 3

b) 642 worked out as under.

1 to 9 = 9
10 to 99 = 90 x 2 = 180
100 to 250 = 151 x 3 = 453
Total = 9 + 180 + 453 = 642

Answer 4

1-9 = 9 digits
10-19 = 20
20-29 = 20...
90-99 = 20..

so far = 9 * 20 + 9 = 189

100-109 = 30
110-119 = 30...
190-199 = 30

so far = 189 + 10 * 30 = 489

200-209 = 30...
240-249 = 30
250 = 3

total = 489 + 30 * 5 + 3 = 642

Answer 5

noof digits = 9 for single digits + 2*90 for 2-digits number + 3*(250-100+1) for 3-digits number
= 9 + 180 + 453
= 642

the answer is letter "B"

Answer 6

b)
9 single digits = 9
90 double digits = 180
151 triple digits = 453

9 + 180 +453 = 642

Answer 7

1-9 = 9 digits
10-19 = 20
20-59 = 80...
60-99 = 80..
100-109 = 30
110-149 = 120...
150-189 = 120
190-209 = 60...
210-249 = 120
250 = 3
total = 9+20+80+80+30+120+120+60+120+3=642
So, the answer is b.
Anyways nice question.
Like it.

Answer 8

A