By Contributor Updated Aug 30, 2022
Chisenbop is a finger‑based arithmetic method originally taught in Korean schools. It enables students to perform quick calculations for numbers 0‑99, improving mental math skills and confidence. Below is a step‑by‑step guide to learning this technique.
Position both hands in front of you, palms facing down, a few inches above a flat surface.
Use the right hand to represent the units place. Place the index finger down to indicate 1; both index and middle fingers down for 2, and so on until 5, where the thumb is down and the other fingers are up.
Keep the thumb down and add the index finger for 6. Continue in this pattern up to 9, always counting the number of fingers down.
To signify 10, lower the index finger of the left hand while keeping the right hand’s fingers and thumb up. Continue counting from 21 upward, using the right hand’s fingers for the units and the left hand’s index for the tens, up to 99.
Practice adding and subtracting the same number repeatedly between 0 and 99. With consistent practice, you’ll be able to perform these operations rapidly without mentally tracking each step.
Multiplication becomes a matter of repeated addition. For example, to compute 8 × 6, start at 0 and add 8 six times to reach 48.
Division can be handled through repeated subtraction. Subtract the divisor until the remainder is less than the divisor. The number of subtractions is the quotient, and the leftover is the remainder. For instance, 50 ÷ 8 equals 6 with a remainder of 2, written as 6 R 2.
To find multiples of 9, hold both hands flat. Assign numbers 1–10 to each finger and thumb. For 9 × 4, fold down finger 4 (the left index). The fingers left of this one give the first digit, and those to the right give the second digit, yielding 36.
