Question 1102238
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I get all the same numbers as you, within a few cents.<br>
Do you know if the answer you got by changing from 35 years to 34 years is the right answer?  That's the answer I get.<br>
I think the 34 is the right number to use, because each of them is making the contributions at the end of each year.  If the first twin started investing at age 21 and made contributions for 10 years, then he is 31 when he stops making contributions; it is then 34 more years to when he is 65.