What is the sum of all four digit integers formed using the digits 2, 3, 4 and 5 (repetition is allowed)  Choose the correct answer:
A) 444440 B) 610000 C) 666640 D) 995456 E) 880000
n = 4 * 4 * 4 * 4= 
<gadget id="calculator">4 * 4 * 4 * 4</gadget>
<output>256</output>
256   <x></x>= (5555+ 2222) / 2= 
<gadget id="calculator">(5555+ 2222) / 2</gadget>
<output>7_777/2 = around 3_888.5</output>
3888.5   Sum= number of integers x average value   n * <x> </x>= 256 * 3888.5 = 711040   answer = 995456
<result>D</result>
What is the sum of all four digit integers formed using the digits 2, 3, 4 and 5 (repetition is allowed)