The "hist" function that I used for the interval numbers included the lower bound of an interval in the count. So M6.0 would be included in the interval M6.0 - M6.5 but M6.5 would not be included. One has to be consistent in defining intervals for fits and doing histograms but the differential rate, R0, is independent on how the intervals are specified.
On can find the number of events greater than or equal to a given magnitude by setting ΔM equal to infinity in the first set of formulas in the last blog which would yield an "M+" function. The number in each interval would be the difference of the function values for its bounds. The differential rate is more useful since it allows one to use different time periods.