In the product 5mab,
(i) 5 is the numerical coefficient of mab.
(ii) the coefficient of ab is 5m.
(iii) m, a and b are the only factors.
Only (i) and (ii) are correct.
Each constant and each literal multiplied together to form a product is called a factor of that product. In a product, if a factor is a numerical quantity, it is called a numerical coefficient of the remaining factors, and if a factor involves variables, it is called a literal coefficient of the remaining factors.
The given product is 5mab. Since 5 is a numerical quantity, it is the numerical coefficient of the remaining factors, which is mab. Hence (i) is correct.
Also, (ii) is correct as ab is the coefficient of 5m in5mab.
(iii) is not correct as m, a and b are not the only factors.