Insert commas in the following numbers. a. 13886 b. 365 c. 719463 d. 40047209 e. 2145739180 f. 1783457

Commas should be placed after every third number in a sequence, if that number has more than three numbers. So, here are your answers:
A. 13,886
B. 365 (no comma because this number has only 3 digits)
C. 719,463
D. 40,047,209
E. 2,145,739,180
F. 1,783,457
P.S. You start placing commas from the final number and then move onto the first one.