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Maths Puzzle
s(D) denotes the sum of all natural numbers less than 100,containing the single digits natural number D as one of its digits.Find S(7)-S(3).option (1)220 (2)330 (3)440 (4)397
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- S(7) = 7+17+27+37+47+57+67+70+71+72+73+74+75+76+77+78+79+87+97= 1188
S(3) = 3+13+23+30+31+32+33+34+35+36+37+38+39+43+53+63+73+83+93= 792
hence S(7)-S(3) = 1188 - 792 = 396
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