By dividing 161 by odd prime numbers, trying to find one that will give a whole number, when we come to dividing 161 by 7 we get the integer 23. So 161 = 7×23 So the two-digit number "a" with the digits reversed was 23, Therefore a = 32, and b = 7. So (ab)² = (32×7)² = 224² = 50176 Edwin