What is the sum of all four digit integers formed using the digits 3 ,4 ,5 and 6 (repetition is allowed) Choose the correct choice from the following.
A) 1279874	B) 1279872	C) 1279875	D) 1279876	E) 1279870
n = 4 * 4 * 4 * 4= 
<gadget id="calculator">4 * 4 * 4 * 4</gadget>
<output>256</output>
256   <x></x>= (6666 + 3333) / 2= 
<gadget id="calculator">(6666 + 3333) / 2</gadget>
<output>9_999/2 = around 4_999.5</output>
4999.5   Sum= number of integers x average value   n * <x> </x>= 256 * 4999.5= 
<gadget id="calculator">256 * 4999.5</gadget>
<output>1_279_872</output>
1279872   answer= 1279872
<result>B</result>
What is the sum of all four digit integers formed using the digits 3 ,4 ,5 and 6 (repetition is allowed)