$0.69/sprint
Add multiples of 10 within 40
Add without crossing the 10 within 40
Add crossing the 10 within 40
Add 2-digit #s & 1-digit #s within 40
Add 2-digit #s within 40 without renaming
Add 2-digit #s within 40 with renaming
Add 2-digit numbers within 40
Add within 40