In multiplication the numbers you multiply are called factors, the answer of multiplication is called the Product.
The product of multiplying a number between 1 and 10 by 9 has no more than 2 digits.
Let's call the two numbers used in the multiplication as Factor 1 and Factor 2, the number between 1 and 10 as Factor 1, and the 9 Factor 2. Factor 1 is also known as Multiplicand, and Factor 2 Multiplier.
METHOD
Step 1. Multiply a number between 1 and 10 by 9
Step 2. First digit of product equals to value of Factor 1 minus 1
Step 3. Second digit of product equals to Factor 2 minus the number obtained in Step 2
Step 4. Combine the numbers in Step 2 and Step 3 together to form the answer.
| Step 1 | Step 2 | Step 3 | Step 4 |
|---|---|---|---|
| 1 x 9 | 1 - 1 = 0 | 9 - 0 = 9 | 09 or 9 |
| 2 x 9 | 2 - 1 = 1 | 9 - 1 = 8 | 18 |
| 3 x 9 | 3 - 1 = 2 | 9 - 2 = 7 | 27 |
| 4 x 9 | 4 - 1 = 3 | 9 - 3 = 6 | 36 |
| 5 x 9 | 5 - 1 = 4 | 9 - 4 = 5 | 45 |
| 6 x 9 | 6 - 1 = 5 | 9 - 5 = 4 | 54 |
| 7 x 9 | 7 - 1 = 6 | 9 - 6 = 3 | 64 |
| 8 x 9 | 8 - 1 = 7 | 9 - 7 = 2 | 72 |
| 9 x 9 | 9 - 1 = 8 | 9 - 8 = 1 | 81 |
| 10 x 9 | 10 - 1 = 9 | 9 - 9 = 0 | 90 |
