@Walina the answer is 220?
In the sample picture we have 2 rows of 2 and in order to put these matches horizontally we use 3×2 matches and also to put these matches vertically we use 3×2 matches. So the product will be 12 matches.
If we had 10 rows of ten we should use 10×11+10×11=220 matches.
(Click on the link for the worked solution)