Question 1140645
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85 times.<br>
Look at the pattern:<br><pre>
66*33 = 2178    2 digits times 2 digits --> 1 7
666*333 = 221778    3 digits times 3 digits --> 2 7's
6666*3333 = 22217778    4 digits times 4 digits --> 3 7's
66666*33333 = 2222177778    5 digits times 5 digits --> 4 7's
...
86 digits time 86 digits --> 85 7's<br></pre>
Here is a demonstration of the result for the case where both numbers are 5 digits; the demonstration for 86-digit numbers will be similar.<br>
{{{66666*33333}}}
= {{{66666*(99999/3)}}}
= {{{66666*((100000-1)/3)}}}
= {{{(6666600000-66666)/3}}}
= {{{2222200000-22222}}}
= {{{2222177778}}}