2 0 1 1 2 0 1 2 × 2 0 1 3 2 0 1 4
Find the number of digits of the number above when stated in decimal representation.
Details and Assumptions
You may use the following approximations
lo g 1 0 2 0 1 1 = 3 . 3 0 3 4 1 2 0 7 0 5 9 6 7 …
lo g 1 0 2 0 1 3 = 3 . 3 0 3 8 4 3 7 7 4 8 8 8 6 …
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Yes, I used the same method.
i did not understood the whole theory behind your formula. can you explain it to me.
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P.S: Here , Every log's base is 10. Note that, lo g 1 0 1 = 0 and, lo g 1 0 1 0 = 1 also , lo g 1 0 1 0 0 = 2
Have you noticed Something? when the number of digits were 1 the result of it's log was 0.
when the number of digits were 2 the result of it's log was 1. and
when the number of digits were 3 the result of it's log was 2.
have you noticed a pattern ? we can measure any number's number of digits using log !
now let us Create a Formula !
I want to find out how many digits are there in the number '1' we can easily tell it's 1 but we should find it using log!
for log 1=0 so, if we add one with it we can find the number of the digit! log 1 + 1 =1 ! now let's try it for 10 and 100.
log 10= 1 hence, log 10+1= 2 , So 10 has 2 digits.
log 100 =2 hence, log 100+1 = 3 , so 100 has 3 digits.
Now, What if the number is something like 2 or 5 or 126 or something?
log 2 = 0.301.. hence log 2+1=1.301... but it has 1 digit! so how can we make 1.301... into 1? we use "floor" ofcourse !! floor is a symbol like this ⌊ x ⌋ It means the highest integer which is smaller than x. like ⌊ 2 . 5 ⌋ = 2 , ⌊ 2 . 1 1 ⌋ = 2 a n d ⌊ 2 . 9 9 9 9 ⌋ = 2
so now we can say, ⌊ lo g 1 0 2 + 1 ⌋ = 1
the same rule applies for all positive integer numbers ! So now we can simply say that , for any natural number 'N' , the number of digits N has is ⌊ lo g 1 0 N + 1 ⌋
Now look at my solution once more ! If you still have problem understanding it let me know!
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Thanks very much for your explanation, but could you explain me how you calculate the log of 2011 and 2013 without the use of a calculator. Thanks.
Great explanation...!!!
It's like this for anti-log there are two main parts.. The one before the decimals and the ones after the decimals.. Consider the log value is x.y (. represents decimal and not multiplication), after anti-log y gives the ans & (x+1) gives the number of digits after which the decimal is to be placed..
can u plz elaborate it am so bad at maths :P
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Have you checked my reply/response to Aditya Vikram's comment ? If you didn't please check ! After checking if u still have troubles understanding it tell me
really nice explanation
i dint undrstood dat theory .....cn u xplain clearly
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Have you checked my reply/response to Aditya Vikram's comment ? If you didn't please check ! After checking if u still have troubles understanding it tell me
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Using Logarithms we can say that, ⌊ lo g 2 0 1 1 2 0 1 2 × 2 0 1 3 2 0 1 4 + 1 ⌋
or, ⌊ lo g 2 0 1 1 2 0 1 2 + lo g 2 0 1 3 2 0 1 4 + 1 ⌋
or, ⌊ 2 0 1 2 lo g 2 0 1 1 + 2 0 1 4 lo g 2 0 1 3 + 1 ⌋
hence, we can find the answer , 13301
P.s: If you have questions please comment below