Question

when a two digit number is multiplied by its unit digits, the product is 336. When the digits are reversed and the new number is multiplied by its new unit digits, the product is 325.If the sum of the digits is 11, find the original two digit number​

Answer 1

9514 1404 393

Answer:

56

Explanation:

In the base-10 number system, the only two digits that have themselves as the least significant digit of their square are 5 and 6.* If multiplying a 2-digit number by the ones digit gives a ones-digit of 6, then the ones digit must be 6.

Similarly, if the ones digit of the product is 5, the ones digit of the number must be 5.

So, the ones digit of the original number is 6, and the ones digit of the reversed 2-digit number is 5. The original number is 56.

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Check

56 × 6 = 336

65 × 5 = 325

5 + 6 = 11

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* Additional comment

These digits are called "automorphs." Automorphs ending in 5 or 6 can be extended to any number of digits. For example, the 3-digit automorph ending in 6 is 376. 376² = 141376. Similarly, the 3-digit automorph ending in 5 is 625. 625² = 390625