How many number of times will the digit '7' be written when listing the integers from 1 to 1000?

Question

anonymous · Answer

well, from 1 to 100, you have it once every tens, and then 11 times in the 70s...... so thats 20 then u have that every 100 .. except the 700s u have to add 100 more.... so id say 100+20*9 = 280 give or take

anonymous · Answer

its answer is 300

anonymous · Answer

Quick way:
How many numbers are there of the forms:
xy7?
x7y?
7xy?

If x, and y can both be 10 different digits (0-9), then there are 10*10 combinations of each of xy7, x7y, and 7xy. That's 100 of each. Add them together, you get 300.

The reason this works is because you're looking for the number of times 7 appears in total, not the number of numbers in which 7 appears.