Level 1
- one digit x one digit
Level 2
- one digit x one digit
Level 3
- two digits + two digits
- two digits - two digits
- three digits - one digit
- three digits - two digit
Level 4
- three digits + three digits
Level 5
- three digits - one digit
- three digits - two digits
- three digits - three digits
Level 6
- three digits + three digits
- three digits - three digits
Level 7
- one digit x one digit
- two digits x one digit