21⋅0.5
Multiply 5 by 1. Place the result in the next column in the result line. There is one result line for each digit in 0.5.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 5 |
Multiply 5 by 2. Place the ones digit (0) in the result line and carry the tens digit (1). There is one result line for each digit in 0.5.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
Multiply 0 by 1. Place the result in the next column in the result line. There is one result line for each digit in 0.5.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
| 0 |
Multiply 0 by 2. Place the result in the next column in the result line. There is one result line for each digit in 0.5.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
| 0 | 0 |
Add the numbers in each column. In this case, add 5+0, then place the 5 in the result line.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
| 0 | 0 | |
| 5 |
Add the numbers in each column. In this case, add 0+0, then place the 0 in the result line.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
| 0 | 0 | |
| 0 | 5 |
Add the numbers in each column. In this case, add 1+0, then place the 1 in the result line.
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
| 0 | 0 | |
| 1 | 0 | 5 |
| 2 | 1 | |
| ⨯ | 0 | .5 |
| 1 | 0 | 5 |
| 0 | 0 | |
| 1 | 0 | 5 |
To find the number of decimal places needed in the answer, add the number of decimal places in the multiplier and multiplicand. In this case, there is a total of 1, so the answer must have 1 decimal places as well.
10.5
Evaluate 21*0.5