If a number is formed by writing integers 1 to 150 one after another, like 12345...150. How many digits does this integer consists of?  Pick one:
A) 150
B) 339
C) 342
D) 359
E) 362
1-digit integers   Number of 1-digit integers (1 to 9) = 9 - 1 + 1= 
<gadget id="calculator">9 - 1 + 1</gadget>
<output>9</output>
9   Number of digits used= (9)(1) = 9   2-digit integers   Number of 2-digit integers (10 to 99) = 99 - 10 + 1= 
<gadget id="calculator">99 - 10 + 1</gadget>
<output>90</output>
90   Number of digits used= (90)(2) = 180   3-digit integers   Number of 3-digit integers (100 to 150) = 150 - 100 + 1= 
<gadget id="calculator">150 - 100 + 1</gadget>
<output>51</output>
51   Number of digits used= (51)(3) = 153   TOTAL # of digits uses = 9 + 180 + 153= 
<gadget id="calculator">9 + 180 + 153</gadget>
<output>342</output>
342   Answer: 342
<result>C</result>
If a number is formed by writing integers 1 to 150 one after another, like 12345...150. How many digits does this integer consists of?