How to calculate the proportion of purchase amount? Answer this question according to the relevant formulas, regulations and calculation methods of mathematical calculation. Examples are as follows: purchasing materials A 800,000 yuan, purchasing materials B 500,000 yuan and purchasing materials C 700,000 yuan. The total purchase amount is 2 million yuan. The proportion of purchased material A is 800,000 yuan divided by 2 million yuan multiplied by 100%, that of purchased material B is 500,000 yuan divided by 2 million yuan multiplied by 100%, which is 25%, and that of purchased material C is 700,000 yuan divided by 2 million yuan multiplied by 100%, which is 35%.