Use each of the five digits $2, 4, 6, 7$ and $9$ only once to form a three-digit integer and a two-digit integer which will be multiplied together. What is the three-digit integer that results in the greatest product

The 3 digit number 642 when multiplied 97 gives the greater product.

Step-by-step explanation:

The greatest product will result by multiplying the smaller 3 digit number with the greater two digit number.

The greater three digit number will be 976 and smaller 2 digit number would be 42

Multiplying

976*42 = 40992   ( descending order number)

679 *24= 16,296  ( ascending order number)

If we take the 2 digit number as 97 and  3digit number 642

Then multiplying

642* 97= 62,274  ( descending order  number)

246 * 79=19434   ( ascending order number)

The 3 digit number 642 when multiplied 97 gives the greater product.