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How many times does the digit one appear from 101 to 200

User Tolulope
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2 Answers

3 votes
118 times
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User Rgv
by
4.1k points
3 votes

Answer:

Explanation:

Let's get the answer first and then we can discuss how it is done. The answer is 119.

There is a problem. The question does not state whether or not 101 is included. If it is 119 is correct. If the question is between 101 and 200 then the answer will be 117.

How was it done? A programming language was used. So it counted by brute force.

From 101 to 120 we get

101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

32 Certainly there must be a quicker way

101 = 2

102 to 109 = 1 * 8 = 8

110 to 119 = 10*2 = 20

111 has an extra 1 = 1

120 has 1

Total 32

From here it gets a bit easier.

121 2

122 - 129 8

total 10

130 1

131 2

132 - 139 8

total 11

140 to 149 11

150 to 159 11

160 to 169 11

170 to 179 11

180 to 189 11

190 to 199 11

total 7 * 11 + 32 + 10 = 119

User Binish
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4.1k points