+0  
 
0
50
1
avatar

A textbook has 1,000 pages. How many of the pages have page numbers whose digits add up to exactly 4?

 

I approached by going by the number of digits.

 

1 digit: 4

2 digit: 13, 22,31, 40

3 digit: 103,130, 301,310 | 112, 121, 211 | 400

 

Am I missing anything because 13 is apparently not the correct answer?

 May 31, 2020
 #1
avatar
0

4 , 13 , 22 , 31 , 40 , 103 , 112 , 121 , 130 , 202 , 211 , 220 , 301 , 310 , 400 , Total =  15 such pages.

 

You just missed 202 and 220.

 May 31, 2020

10 Online Users

avatar
avatar