Question

A new colony was built and the builder give contract to a sign maker to number the buildings from number 1 to 500 how many zeros will he need.

Answer 1

Number of zeros:
10 - 90 = 9
100 = 2
110 - 190 = 9
200 = 2
210- 290 = 9
300 = 2
310 - 390 = 9
400 = 2
410 - 490 = 9
500 = 2
101 - 109 = 9
201 - 209 = 9
301 - 309 = 9
401 - 409 = 9
Total = 91

Hope it helps... 

Answer 2

Needs 50 at the end in the units column--10,20, etc. to 500.

Needs another 40 for the tens holder--100,101,102,103...401,402,403...
90.