Method of Vietnamese Diagram: Double the Divisor 3 Times
Method of International Diagram: Double the Divisor 3 TimesMethod of Vietnamese Diagram: Double the Divisor 5 TimesIt's Easy!
Step 1 - Double, double, double.
Step 2 - Subtract off multiples.
Step 3 - Add up your answer."
Photos source: Nguyen Thi Lan Phuong, http://321math.blogspot.com