Sophie started with a whole number she repeatedly added 1.9 until she ended with 40 where did she start?

Question

please help me I’m very stuck!

Answer 1

If she started with a whole number and ended with a whole number she must have added a whole number!

The sum of all the 1.9's must be a whole number!

ten times 1.9 (19) is the first one

40 - 19 = 21