@howie_hua D minutes in an hour = 60 x 7 days a week. Multiply 6x7 = 42. Add the zero on = 420. 24 hours in a day so add two zeros on = 42000. Half it = 21000. Half it again is just over 10000. Far less than B.
B is the biggest number. Only using the simple times table and zeros, it’s easy.