Subtraction is defined as the process of finding the difference between two numbers or the taking of a part of a number from itself and finding how many are left. The number from which another is taken is known as the minuend, and the number taken from another is known as the subtrahend. The result obtained by taking one number from another is called the remainder.
Substraction rules use two types of movements:
Cancel: consists in removing beads from the middle bar.
Return: after removing a 10-units bead or a 5-units bead, consists in moving down an altobead or move up a hypobead .
Ideally, substracting is achived simply canceling beads (see the first column), but sometimes there are not enoght beads to cancel.
In general, as in additon, there are 18 guides for subtraction. The student will soon find that they are the reverse of those given for addition:
| −1 | cancel 1 | cancel 10 return 9 |
|---|---|---|
| −2 | cancel 2 | cancel 10 return 8 |
| −3 | cancel 3 | cancel 10 return 7 |
| −4 | cancel 4 | cancel 10 return 6 |
| −5 | cancel 5 | cancel 10 return 5 |
| −6 | cancel 6 | cancel 10 return 4 |
| −7 | cancel 7 | cancel 10 return 3 |
| −8 | cancel 8 | cancel 10 return 2 |
| −9 | cancel 9 | cancel 10 return 1 |
We place 1 ten and 7 units.
−8: cancel 10, return 2. Firstly, we cancel 10.
Secondly, we return 2.
Result: 9.
We place 3 thousands, 5 hundreds, 2 tens and 7 units.
−4: cancel 5, return 1.
−8: cancel 10, return 2. Were cancel 10 is obtained from cancel 50, return 40.
−9: cancel 10, return 5, cancel 4.
Result: 2543.
Click on this link to practice the substraction with one figure.
Click on this link to practice the substraction with more figures.
