Division on the Cranmer Abacus Sara Larkin Math

Division on the Cranmer Abacus Sara Larkin Math Consultant Iowa Educational Services for the Blind and Visually Impaired Resource used: Millaway, S. M. (2002). Abacus basic competency: A counting method. American Printing House for the Blind.

Prerequisites • The student must know the multiplication tables • The student should be aware of terms used in division such as dividend, divisor, quotient, and remainder

Abacus Skills • The student must be able to set numbers on the abacus • The student must be able to read numbers on the abacus • The student must be able to demonstrate an understanding and proficiency in the use of the Rules for subtraction on the abacus

Setting Up Division • The entire abacus is used • In 92 ÷ 4 = 23, the dividend is 92, the divisor is 4, and the quotient is 23. • In other words, the dividend ÷ divisor = quotient • The dividend is set on the extreme right • The divisor is set on the extreme left • The quotient will end up between the two with any remainder left all the way to the right • There will be an empty rod between the quotient and the remainder

Dividing • Check to see if the divisor will go into the first digit of the dividend • If it does, move the right index finger from that digit over two digits to the left and place the answer • If it doesn’t go into the first digit, move the right index finger over to the next digit right. Use the two digits as a two digit number to see how many times the divisor goes into that two digit number. Move that right index finger sitting on the 2 nd digit over two digits to the left and place the answer • Multiply the answer with the divisor and subtract from the dividend • Repeat this process until no more division can be done

Practice Dividing • Group A • 69 ÷ 3 = 23 • 40 ÷ 4 = 10 • 82 ÷ 2 = 41 • Group B • 95 ÷ 5 = 19 • 376 ÷ 8 = 47 • 1468 ÷ 2 = 734

More Practice • Group C • 315 ÷ 7 = 45 • 810 ÷ 6 = 135 • 2075 ÷ 5 = 415 • Group D • 58 ÷ 3 = 19 r 1 • 439 ÷ 7 = 62 r 5 • 5934 ÷ 8 = 741 r 6