In order to calculate this rate of growth in m/min, the first step by calculating how many minutes are there in one year using this formular. (365days/year*24hours/day*60minutes/hour)= 525600minutes/year. The second step is to convert 3mm into meters. Keeping in mind that 1000mm make one meter, you can divide 3mm by 1000 which is equal to 0.003m. The third step is to calculate (0.003/525600) in order to find out how many minutes it takes the tree to grow by one meter. Therefore the growth rate of this tree is (0.003meters/year*1/525600years/minute) and the answer can be expressed as 5.7*10^9m/min