[header] How to recognize the type of a reaction [title] Count the number of reactants. [step] A combination/synthesis reaction is aptly named because it is a reaction where two or more products combine together to form one new product. Remember that the reactants of an equation are always on the left side of the arrow. 
[substeps] Many reactions have just two reactants, but you can have combination reactions with more than two reactants. [title] Verify that there is only one end product.