Chain

One running total

Numbers arrive one after another and you carry the total. Nothing is written down, and the answer is only asked for at the end.

How the numbers arrive

Digits per number2Each number falls between 10 and 99.Numbers per chain5How many arrive before the total is asked for.Time on screen0.8sHow long each number stays up before the next one.Chains per run5How many you answer before the run ends.

Operations

Chains read strictly left to right, so there is no precedence to get wrong. The running total never goes below zero.

For example

61 − 34 + 80 − 24 − 70