$0.59/sprint

• 2, 3, & 4 as subtrahends (3)
• 5 as a subtrahend (3)
• 6 as a subtrahend (3)
• 7 as a subtrahend (3)
• 8 as a subtrahend (3)
• 9 as a subtrahend (3)
• Subtract within 100 taking from the 10
• Subtract neighboring ones digits within 100
• Subtract crossing the 10 within 100
• Add and subtract crossing the 10 within 100
• Subtract 1 more or 1 less than a multiple of 10