For example, the first stack of pennies starting on the left side of the table is just one penny by itself. Beside it, to its right is a stack of 2 pennies.
[header] How to add a consecutive series of numbers in your head [title] Imagine the numbers. [step] Let's suppose that you want to add all the numbers from 1 to 100 in your head. Imagine that on a table in front of you you have arranged stacks of pennies, in a long neat row left to right, to equal each of these numbers.