That’s why it’s easier. if you’re going left to right you have to not only figure out the sum of the first number position, but also if there’s a 1 to carry or not. Going right to left you only have to focus on one 1 digit add at a time and you already know if there’s a carry by looking at the last addition.
Its technically true that it decides token at a time but it also takes previous tokens into account.
That’s why it’s easier. if you’re going left to right you have to not only figure out the sum of the first number position, but also if there’s a 1 to carry or not. Going right to left you only have to focus on one 1 digit add at a time and you already know if there’s a carry by looking at the last addition.