Question -
Answer -
Here,
1 ×10 1= remainder obtained by dividing 1 × 1 by 10
= 1
3 ×10 7= remainder obtained by dividing 3 × 7 by 10
= 1
7 ×10 9= remainder obtained by dividing 7 × 9 by 10
= 3
So, the compositiontable is as follows:
| ×10 | 1 | 3 | 7 | 9 |
| 1 | 1 | 3 | 7 | 9 |
| 3 | 3 | 9 | 1 | 7 |
| 7 | 7 | 1 | 9 | 3 |
| 9 | 9 | 7 | 3 | 1 |
From the table we canobserve that elements of first row as same as the top-most row.
So, 1 ∈ S is the identity element with respect to ×10
Now we have to findinverse of 3
3 ×10 7= 1
So the inverse of 3 is7.