Number RiddlesOnline version A quick number puzzle to test your skills. by Arnab Biswas 1 I’m a two-digit number where the tens digit is twice the ones digit and the digits differ by 1. Hints 1 The ones digit is 1 and the tens digit is 2, giving 21. 2 The tens digit is twice the ones digit. 3 Think of a number between 10 and 99. 2 Many consider me unlucky , but I am special. If you subtract my smaller digit from the higher digit you get the first prime number , and if you add them , you get the first composite number 3 I am an even number , but I am prime. 4 Multiply me by any number from 1 to 10 , and then add up the digits of the product , you will find me again, 5 if you add me before a number , the number doe not change ,but if you add me after a number ,it becomes much bigger,
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