Question 1114944
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The number is the coefficient of the {{{(a^6)(b^4)(c^3)(d^7)}}} term in the expansion of {{{(a+b+c+d)^20}}}.<br>
That number is the multinomial coefficient (20;6,4,3,7) (my notation) which is calculated as<br>
{{{(20!)/((6!)(4!)(3!)(7!)) = 4655851200}}}<br>
So the method used by the other tutor is also valid.