Base 4 Numbers
создатель Allison Lindhorst

1. Most Difficult
1.1. Base 4 pieces
1.2. Subtraction
1.3. Multiplication
1.4. Division
1.4.1. Remainders
2. Closed?
2.1. Addition
2.1.1. Yes?
2.1.2. No?
2.2. Subtraction
2.2.1. Yes?
2.2.2. No?
2.3. Multiplication
2.3.1. Yes?
2.3.2. No?
2.4. Division
2.4.1. Yes?
2.4.2. No?