Technically only 1...
If you have to use 4 rows there is only one option;
1 1 1 2
1 1 2 1
1 2 1 1
2 1 1 1
Each number represents the total kids in a row.
1st number is row 1 second number is row 2 etc.
If you can use 2 or 3 rows there are some more answers.
He will never reach the full foot, this is because if he travels 1/2 of the distance of the previous jump each time there will always be a fraction that is unaccounted for.
