Why was Mr. Darling calculating the money that he had ?

The Darlings were not rich, and yet, Mr. Darling loved to have everything his neighbors had. As a result, he had to be careful with his calculation, so he would have enough money to pay for their lifestyle.

Mrs. Darling loved to have everything just so, and Mr. Darling had a passion for being exactly like his neighbours; so, of course, they had a nurse. As they were poor, owing to the amount of milk the children drank, this nurse was a prim Newfoundland dog, called Nana, who had belonged to no one in particular until the Darlings engaged her.