Find the value of A.
Answer:
5
- We see that A, when multiplied by A, gives A at the ones digit of the product.
- Let us multiply each digit from 1 to 9 with itself and look at the products.
- 1 × 1 = 1
- 2 × 2 = 4
- 3 × 3 = 9
- 4 × 4 = 16
- 5 × 5 = 25
- 6 × 6 = 36
- 7 × 7 = 49
- 8 × 8 = 64
- 9 × 9 = 81
- Now, let us calculate the value of AA × A for 5 and 6.
   5 5
×    5
---------
2 7 5
---------
   6 6
×    6
---------
3 9 6
--------- - On comparing the products with those given in the question, we see that the value of A is 5.
From the above list, we see that A = 5 or 6.