Thread: help in my sequence

(2,4,8,16,32,64,128,256,512,1024,......)

if i have a number i want to know if it is in the sequence or not
but i don't want the way which i will divide the number by 2 till i found it 2 or not i want a function from one or two steps to know if this number is from sequence or not

Take the log using base 2. If the answer is an integer than your number is in the sequence

Originally Posted by e^(i*pi)

Take the log using base 2. If the answer is an integer than your number is in the sequence

thx but what meant by log

Look at .

Your sequences is . By log I mean logarithm which is the inverse of exponentiation. where x is the number you're wondering whether or not is in sequence

thx this will help me alot
thx also plato but i think the second method is easier

That's very strange! You say that you do not know what a logarithm is but you think it will be easier to take the logarithm?

If you really do not know about logarithms (especially taking the logarithm, base 2) I would recommend repeatedly dividing by 2. If you eventually arrive at 1 without any fractions, the number is a power of 2.

Originally Posted by HallsofIvy

That's very strange! You say that you do not know what a logarithm is but you think it will be easier to take the logarithm?

If you really do not know about logarithms (especially taking the logarithm, base 2) I would recommend repeatedly dividing by 2. If you eventually arrive at 1 without any fractions, the number is a power of 2.

i searched for lagorithm and learned it thx very much