Too Small to Fail — Morris Gleitzman

1 boy. 1 girl. 1 camel. Squillions of dollars. A plan that can't fail. Or can it? Oliver's parents own a bank. This makes them very rich, very important and very busy. Oliver, on the other hand, is terrible at maths and aspires to nothing more than owning the puppy that he frequently visits at his local pet shop. When a mysterious woman threatens to harm the puppy if Oliver can't make her fortune (unfortunately, Oliver's parents seem to have misplaced her investment. Something to do with some stuff on the news), Oliver hatches a plan which will take him further than he ever imagined…