On the last page, we've learnt to convert from binary to denary. Oftentimes, we need to convert a number from denary to binary, not the other way around.
To do the conversion, we need to keep dividing the denary number by, recording the remainders of the operation, until the quotient is zero. The binary number is the remainders in reverse.
Believe it or not, this is simpler than it sounds! It can be illustrated by the gadget on this page. Type in the number and watch it converted! (I have room for ten rows, so maximum of 512 is allowed.)