118 or 119
There are currently 118 known elements.
117 elements
By 1869, a total of 63 elements had been discovered.
Now are known 118 chemical elements.
112
In 1818 there were 49 known and accepted (by the scientific community) elements.
Today are known 118 chemical elements; 98 are considered as natural elements (but some have also and an artificial origin).
There were about 63 known elements.
Today (July 2013) 118 chemical elements are known.
63 elements had been discovered so far.
This question is a little ambiguous. If you mean 'how many elements have mass,' the answer is 'all elements have mass.' There are 117 known elements, and scientists theorize that there may be as many as 130 or more.
I believe there were 55 or 56 known elements then.