This is a simple training programm for multiplication of (up to) two-digit integers.
This is probably not for anzan (mental arithmetic) per se, but still helps.
It has three courses:
- Genral
- Indian
- Mixed
In the Indian course (2), probelms are designed to work with so called Indian calculations.
There are three types.
- The tens place of a and b match and the sum of the units place of a and b is 10 (eg.
$97 \times 93$ ) - The tens place of a and b match and the sum of the units place of a and b is NOT 10 (eg.
$78 \times 76$ ) - the units place of a and b match and the sum of the tens place of a and b is 10 (eg.
$79 \times 39$ )
In case 1,
- Multiply the tens place of a with the sum of the tens place of b and 1 (
$9 \times (9 + 1)= 90$ ) - Join this value with the product of the units place of a and that b (
$7 \times 3$ )
eg.
In case 2,
- Add the unit place of b to a to gain c (
$78 + 6 = 84$ ) - Multiply this value c (
$84$ ) with the tens place of b (9) ($84 \times 7 = 588$ ) - Obain the product of the units place of a and b (
$8 \times 6$ ) to 10-fold of the product above ($588 \times 10$ )
eg.
In case 3,
- Add the unit places of b to the product of the tens place of a and b (
$7 \times 3 + 9$ ) - Join the product of the units place of a and b.
eg.
In general,
- Join the product of the tens place of a and b and that of the units place of a and b
- Obtain the sum of the product of the tens place of a and the units place of a and b and that of the units place of a and the tens place of b
- Add the numbers by adjusting the digits
eg.