How a Hundred Chart Is Organized

The big idea

A standard hundred chart has 10 numbers in each row. Moving one square right increases a number by 1, and moving one square left decreases it by 1. Moving one row down increases by 10; moving one row up decreases by 10.

These changes come from the chart layout, so they work from every interior square. Longer moves combine the same small changes.

Worked example

Start at 37. Moving two squares right gives 37 + 2 = 39. Then moving three rows down gives 39 + 30 = 69.

A diagonal move down and right changes by 11 because it combines +10 and +1. A diagonal move down and left changes by 9 because it combines +10 and −1.

How children may show it

A child may trace a route, write the change beside each arrow, use repeated addition, or compare the tens and ones digits in a column. Highlighting a column reveals that the ones digit stays the same while the tens digit changes.

Common mix-up

Some charts begin with 0 while others begin with 1, and some have a different number of columns. The visible layout determines the move size. Check the chart before applying a memorized rule. Also watch row-end moves: stepping right from 40 may wrap to 41 in the next row rather than remaining visually adjacent in the same row.

Try it together

Choose a starting number away from the edges. Give a short route such as down, down, left, right, and ask for the ending number without moving a marker. Then use the chart to verify. Reverse the challenge by naming a start and end and finding more than one valid route.