# How to divide by 3.5 by multiplying

I want to divide a variable by 3.5, only through multiplying it with a value under 1. How do I find out what I should multiply by?

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$3.5=\frac{7}{2}$, so dividing by $3.5$ is multiplying by its inverse. So what you want is $\frac{2}{7}$.
Division by a number $x$ is the same as multiplication by its reciprocal, $\frac{1}{x}$. So, if your variable is $y$, and you want to calculate $$\frac{y}{3.5}$$ it is equal to $$\left(\frac{1}{3.5}\right)\times y$$ so the value "under 1" you are looking for is just $3.5$ again, and the quantity you should multiply your variable by is $$\frac{1}{3.5}=\frac{1}{3.5}\times 1=\frac{1}{3.5}\times\frac{2}{2}=\frac{2}{7}$$