How many integers between 324,700 and 458,600 have tens digit 1 and units digit 3? (A) 10,300 (B) 10,030 (C) 1,353 (D) 1,352 (E) 1,339

458600
324700

Diff 133900

Since the last two digits have to be 13, discounting those digits, it seems to be the case that there will be 4586-3247=1339 such cases (this is true for any other combination of last two digits I think).

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this happens exactly every 100th integer - no variation at all there, each "successful" integer is exactly 100 greater than the last one - and the total pool of integers under consideration is a multiple of 100, so there won't be any pattern interrupts. therefore, you can just divide the total # of integers by 100 and you're good.

if you were considering runs of integers that weren't multiples of 100, such as, say, the integers from 134,523 to 135,508, then you'd have to worry about the behavior at the boundaries.