The numbers 3-11 are in a random pile to the left of a 3 x 3 grid.
Drag 8 of the 9 numbers from the pile into the spaces in the grid.
Your task is to arrange the numbers so that the sum of the 3 numbers in each direction adds up to the number 21.
Use the "spare" space to help you move the numbers around.
*Take care, when the final number is added the grid becomes "frozen".
Don't worry if you can't find all 7 but how many can you manage?
To restart the activity just refresh the page.