What is the least number of digits (including repetitions) needed to express 10^400 in decimal notation? Pick one.
A) a) 401	B) b) 100	C) c) 101	D) d) 1000	E) e) 1001
10^n is a decimal number with a 1 followed by n zeros.   So 10^100 will include 400 0's + 1 digit for 1 = 401   So the answer is a) 401
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What is the least number of digits (including repetitions) needed to express 10^400 in decimal notation?