After she worked out the problem, she had a discrepancy (disagreement) of about 45% between her estimate and the quotient.
That's a lot ! There's almost definitely a major mistake somewhere, and there really isn't any way to tell whether the mistake is in the estimate or in the quotient.
My answer to the question is that Lilly has to go all the way back to the beginning, and do the whole thing again. Only this time, she has a harder job to do: She not only has to make another estimate and work out the division problem again. This time, she also has to find the mistake that she made the first time ... and there may be more than one of them.
